See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/341294961 Infidelity and Its Associated Factors: A Systematic Review Article in Journal of Sexual Medicine · August 2019 DOI: 10.1016/j.jsxm.2019.04.011 CITATIONS 35 READS 698 5 authors , including: Some of the authors of this publication are also working on these related projects: Necessity for Hepatitis B .... View project Shahroud School Children Eye Cohort Study (SSCECS) View project Arezoo Haseli Kermanshah University of Medical Sciences 17 PUBLICATIONS 137 CITATIONS SEE PROFILE Mohammad Shariati Tehran University of Medical Sciences 81 PUBLICATIONS 2,373 CITATIONS SEE PROFILE Afsaneh Keramat 150 PUBLICATIONS 1,620 CITATIONS SEE PROFILE Mohammad Hassan Emamian Shahroud University of Medical Sciences 197 PUBLICATIONS 7,615 CITATIONS SEE PROFILE All content following this page was uploaded by Arezoo Haseli on 04 August 2023. The user has requested enhancement of the downloaded file. ORIGINAL RESEARCH & REVIEWS BEHAVIOR In fi delity and Its Associated Factors: A Systematic Review Arezoo Haseli, MSc, 1 Mohammad Shariati, MD, 2 Ali Mohammad Nazari, PhD, 3 Afsaneh Keramat, PhD, 4 and Mohammad Hassan Emamian, MD, MPH, PhD 5 ABSTRACT Background: In fi delity can be facilitated and/or inhibited as a result of interrelations among multilevel contexts. Despite the existence of numerous studies about in fi delity, there is no developmental model that considers multilevel contexts of factors associated with in fi delity. Aim: To review published articles addressing factors associated with in fi delity and to apply the ecological model to these factors. Methods: A systematic review of the literature was conducted using the PubMed, Scopus, Web of Science, and PsychoInfo. Literature search was restricted to articles published in English up to June 2018. All quantitative and full-text studies that addressed associated factors with in fi delity were included. This study was conducted following PRISMA guidelines. Main Outcome Measures: This article reports a review of the literature on the factors associated with in fi delity based on the ecological model. Results: We retrieved 5,159 titles, of which 82 were quali fi ed after the qualitative synthesis. The Ecological Couples Systems Diagram (ECSD) is proposed as a developmental model similar to Bronfenbrenner ’ s Bioecological Systems Model. There was an inconsistency between variables of microsystem and in fi delity engagement. However, the results of some studies indicated the impact of demographic factors, personality traits, and sexual information on in fi delity, considering partner characteristics. Variables belonging to a mesosystem had a more stable association with in fi delity than those from other systems. In addition, the review reveals the complexity of in fi delity, associated with following factors: 68.3% (n ¼ 56) of the studies were based on microsystem variables, 48.8% (n ¼ 40) used mesosystem variables, 19.5% (n ¼ 16) used exosystem variables, 26.8% (n ¼ 22) used macrosystem variables, 6.1% (n ¼ 5) used chronosystem variables, and 50% (n ¼ 41) included variables from 2 or more levels. Clinical Implications: The ECSD can be used not only for assessing couple compatibility in premarital counseling, but also for consulting couples who want to have a long-term romantic relationship. As a potential clinical application, therapists can use the ECSD to assess unfaithful clients and their partners, improving the quality of counseling. Strengths & Limitations: This study reveals different environmental layers of various variables related to in- fi delity. Determining the effect size of variables associated with in fi delity was not possible due to the hetero- geneity of in fi delity assessment tools and test analysis. Conclusion: Apparently, incompatibility of interpersonal characteristics is more likely associated with in fi delity than incompatibility of intrapersonal characteristics. It is important to consider couple compatibility before starting an exclusive relationship, such as marriage, for individuals who intend to maintain a long-term exclusive romantic relationship. Haseli A, Shariati M, Nazari AM, et al. In fi delity and Its Associated Factors: A Systematic Review. J Sex Med 2019;16:1155 e 1169. Copyright Ó 2019, International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved. Key Words: In fi delity; Extradyadic; Unfaithful; Affair; Ecological Model Received October 29, 2018. Accepted April 22, 2019. 1 Student Research Committee, School of Nursing and Midwifery, Shahroud University of Medical Sciences, Shahroud, Iran; 2 Department of Community Medicine, Tehran University of Medical Sci- ences, Tehran, Iran; 3 Department of Nursing and Midwifery, Shahroud University of Medical Sciences, Shahroud, Iran; 4 Reproductive Studies and Women ’ s Health Research Center, Shahroud University of Medical Sciences, Shahroud, Iran; 5 Center for Health Related Social and Behavioral Sciences Research, Shahroud University of Medical Sciences, Shahroud, Iran Copyright ª 2019, International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.jsxm.2019.04.011 J Sex Med 2019;16:1155 e 1169 1155 INTRODUCTION In fi delity has been de fi ned as “ a violation of a couple ’ s assumed or stated contract regarding emotional and/or sexual exclusivity. ” 1 The secret romantic activity with a secondary partner and violation of relationship exclusivity, such as marriage, often lead to deep pain, loss of trust, and uncertainty. 2 In addition, in fi delity is considered among the threatening factors affecting the stability, performance, and tolerance of couple relationships and is one of the most frequently cited reasons for marital breakdown and health problems. 3 The results of a 2007 meta-analysis of 50 studies showed a lifetime prevalence of in fi delity in 34% of men and 24% of women. 4 Numerous studies have addressed the factors correlated with in fi delity. For example, demographic variables, such as gender, age, and education, can be predictive of in fi delity engagement. 5,6 Other variables, such as insecure attachment, relation dissatis- faction, 7 and higher socioeconomic status, 8 have been associated with high levels of in fi delity. Today, religious af fi liation can play an important role in engaging in in fi delity. 9 Clearly, a compre- hensive understanding of in fi delity and its interactions with the surrounding environment requires investigation of related fac- tors. People ’ s behaviors are affected by interpersonal factors, social contexts, organizational structure, and processes because of spending a major part of a person ’ s life within them. 10 Given that in fi delity behavior can be facilitated and/or inhibited as a result of interrelations among multilevel contexts, the social-ecological systems theory can provide an appropriate description of this behavior. 3 The ecological model is likely one of the few methods that can describe the interactions among various factors and components of phenomena or behaviors like in fi delity in real life. In addition, it provides an overview of human behavior instead of a single-dimensional view. 11 The present study had 2 main objectives: to clarify and summarize the variables associated with in fi delity and to apply the ecological model proposed by Bronfenbrenner to in fi delity. METHODS This systematic review was carried out following PRISMA guidelines. 12 Search Strategy The PubMed, Scopus, Web of Science, and PsychoInfo da- tabases were searched from inception to June 2018 for papers published in English using the following search terms: “ extra- marit* or unfaithful* or in fi delity or disloyal* or betrayal or affair or cheating ” or “ experiencing relationship distress ” or “ sexual activity outside marriage ” or “ extradyadic involvement ” or “ secret romantic realation ” AND “ relat* or relevant* or associate* or af fi liate or predict* or correlate* or dependent* or risk ” . The search strategy used for searching in the one of the databases is described in Appendix A. The reference lists of the articles included in this review were manually screened for other possibly eligible studies. Eligibility Criteria In this study, we considered all types of in fi delity, including sexual and/or emotional in fi delity, in both the real world and virtual worlds. To evaluate the factors associated with in fi delity, the eligible studies had to meet the following criteria: (i) having a (part of) quantitative study design, addressing the factor(s) associated with in fi delity; (ii) being reported in English; (iii) and being a complete manuscript (not abstract only). Conference abstracts, case reports, reviews, and editorials were excluded. In addition, studies conducted in a speci fi c group of populations, such as infertile women, were considered nonrepresentative samples and excluded from this review. Studies in which the results were a comparison of factors associated with sexual and emotional in fi delity, and not in fi delity engagement itself, were also excluded. Study Selection and Data Extraction 2 authors (A.H. and M.S.) screened the titles and abstracts of all retrieved records, and then the full texts independently. Cohen ’ s k index was calculated. When there was disagreement on whether a study met the inclusion criteria, the article was reviewed by a third author (A.K.) and then selected or discarded by consensus. The following variables were then extracted from the studies included in the systematic review by A.H. and M.S.: author ’ s name, year of publication, country, study design, sample size, gender, orientation, age, tool to assess in fi delity, and pri- mary results (variable predicting/associating in fi delity, effect size), as well as ecological level proposed by Bronfenbrenner 10 : microsystem, mesosystem, exosystem, macrosystem, or chro- nosystem. To synthesize the results, the factors associated with in fi delity were classi fi ed based on the ecological model, and then this model was applied to in fi delity. Assessment of Methodologic Quality All 82 included articles were assessed using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. The STROBE checklist includes 22 items. Scores range from 0 to 22, with higher scores indicating higher quality. 13 The quality of studies is also classi fi ed into 3 groups based on STROBE scores: low ( < 6.5), medium (6.5 to 16), and high ( > 16). This assessment was conducted indepen- dently by 2 researchers (A.H. and M.S.); inconsistencies were settled by the third author (A.K.) and then by consensus. RESULTS Study Selection A fl owchart of the study is presented in Figure 1. A total of 3,026 studies were retrieved from the PubMed, Scopus, Web of Science, and PsychoInfo databases. After 1,003 duplicates were J Sex Med 2019;16:1155 e 1169 1156 Haseli et al removed, 2,023 reports were screened for the titles and abstracts. From this screening, 1,915 citations irrelevant to the research topic were excluded. Based on full-text reviews of the 108 remaining studies, 29 articles were excluded, including 22 studies involoving qualitative research, 1 study conducted in infertile women who were not a representative sample, and 6 articles reporting factors associated with sexual in fi delity compared with emotional in fi delity. The remaining 82 studies were included in this systematic review. Of note, 6 studies had a mixed-method design, but the quantitative part met our inclu- sion criteria, and only the quantitative sections of these studies were reviewed. Assessment of Methodological Quality Cohen ’ s k index was 0.798, indicating substantial agreement between 2 raters. 14 The quality assessment is detailed in Appendix B. The quality of the included studies ranged from 9 to 18.1 out of 22 for the 82 studies evaluated with the STROBE checklist. Thirteen studies (15.9%) were deemed of high quality (score > 16), and the remainder (84.1%) were of medium quality (score 9 to 16). These results show that in general, the quality of the included studies was moderate to high. Characteristics of Included Studies The articles reviewed, published between 1979 and 2018, are characterized in Appendix C. Eighty-nine percent of the studies were of cross-sectional design (including 8.5% online cross- sectional and 7.3% mixed-method studies), and 11% (n ¼ 9) were of longitudinal design. The majority of the studies were conducted in the United States (46; 56.1%), with 12 (14.6%) conducted in Asia, 11 (13.4%) conducted in Africa, 6 (7.3%) conducted in Europe, and 2 (2.4%) conducted in multiple continents. The location of 2 studies (2.4%) was unclear. Regarding gender, 65 studies (79.3%) included both men and women, 11 (13.4%) included only men, and 6 (7.3%) included only women. Finally, 22 studies (26.8%) included heterosexual participants, 10 (12.2%) included participants with different types of sexual orientation, and 50 (61%) did not report infor- mation about sexual orientation. The authors of the selected articles assessed in fi delity using 21 different instruments and items derived from self-reports or self-made questionnaires (Appendix C). The most frequently used questionnaires were the Dyadic Adjustment Scale (Spanier 1976) and the Susceptibility to In fi delity Scale (Buss and Shackelford, 1997). Records identified through database searching (n = 3,026) Records removed for duplication (n= 1,003) Studies included in quality appraisal (n=82) g n i n e e r c S d e d u l c n I y t i l i b i g i l E n o i t a c i f i t n e d I Additional records identified through other sources (n = 0 ) Records screened (n = 2,023) Records excluded after screening titles and abstracts (n = 1,915) Full-text articles assessed for eligibility (n = 108) Full-text articles excluded, with reasons (n = 29) -Qualitative research (n=22) -Not representative sample (infertile women) (n=1) -The results present associated factor with sexual compared with emotional infidelity with Reaction Infidelity Questionnaire (n=6) Studies included in qualitative synthesis (n = 82) Figure 1. Flowchart of study selection. Figure 1 is available in color online at www.jsm.jsexmed.org. J Sex Med 2019;16:1155 e 1169 In fi delity and Its Associated Factors 1157 According to the ecological model, microsystem variables were assessed in 56 studies (68.3%) of studies, mesosystem variables were assessed in 40 studies (48.8%) of studies, exosystem vari- ables were assessed in 16 studies (19.5%) studies, macrosystem variables were assessed in 22 studies (26.8%), chronosystem variables were assessed in 5 studies (6.1%) studies, and 2 or more levels were assessed in 41 studies (50%). RESULTS AND DISCUSSION Applying the Ecological Model to In fi delity Applying ecological approaches is particularly suitable for factors associated with in fi delity. Some unique behaviors such as in fi delity, which have a complex interaction with the environ- ment, 10 sometimes are not appropriately ascribed to an in- dividual ’ s behavior and may be ascribed to a new system. 15 Couple relationships are inherently interdependent, and each partner ’ s behavior can affect the other ’ s. Therefore, it is dif fi cult to understand the behavior of 1 partner without considering the other. 16 A new concept was developed in which a couple ’ s system acts as a union system in dyadic exclusivity. Based on this concept, a partner ’ s characteristics and relations may (not) pro- vide a context for his or her partner to engage in in fi delity. In other words, in fi delity often (not always) is a product of 2-sided couple ’ s behaviors, although it may be accomplished by 1 or both partners. Based on this hypothesis and the overview of primary studies, a union system comprising 2 microsystems (individual and his or her partner) was developed, termed the Ecological Couples System Diagram (ECSD) (Figure 2). Other systems (eg, exosystem, macrosystem, chronosystem) affect the ECSD. Jones et al 17 has presented a similar sexological system that provides an ecological model and assessment approach for sex therapy. In comparison, the ECSD is a conceptual model of associated factors with in fi delity as a union system that interacts with all different systems in ecological systems theory. Consistent with this idea, Zayas et al 16 noted that a partner ’ s personality is a powerful situational factor in predicting individual behavior. In addition, satisfaction with romantic relationships is in fl uenced by the extent to which a partner complies another one ’ s most important needs. 18 Based on the ECSD, incompatibility in some couples ’ char- acteristics is more likely than incompatibility in some individual ’ s characteristics to lead to engaging in in fi delity, as clearly reported in some primary studies. For example, the role of income level in the prediction of in fi delity depends on partner ’ s income, 19 and also on personality traits, 20 attachment style, 21 sexual values, 3 and other characteristics. Thus, these variables have a dyadic effect on in fi delity engagement. 16,19 e 21 In fact, it seems that incompatibility within a couple can predict in fi delity engagement. This result is con fi rmed by the Couple’s Mesosystem process process process process process Partner 1 Partner 2 Microsystem Microsystem Time : Chronosystem Marital informaon Couple relaonship Sexual sasfacon Aachment style Opportunity: Social media Occupaon Urban residence Home instability Social life Travel Religion Spiritual acvies Race Ethnicity Gender role, equity and norm Cultural masculinity Individual and partner Characteriscs: Socio-demographic Psychological and biological factors Personality traits Sexual informaon Atudes toward infidelity Infidelity experience Sexual funcon and dysfuncon Alcohol consumpon Parent’s characteriscs: Infidelity, divorce and marital sasfacon Figure 2. The Ecological Couple's Systems Diagram. J Sex Med 2019;16:1155 e 1169 1158 Haseli et al cognitive dissonance theory, 22,23 which has reported in- compatibility within the couple as one of the most common causes of in fi delity. Couple incompatibility can be in education, economic status, religiosity, customs, sexual values, sexual attraction, and communication. Incompatible couples engage in in fi delity more than others, which leads to disconnection in couple relationship, as if they have never been actually married. 24 The understanding and response of the 2 partners in interacting with other systems, such as exosystems, macrosystems, and chronosystems, differ when there is incompatibility within the couple. Therefore, incompatibility will be created not only within the couple, but also between the couple and other sys- tems. Consequently, these individuals may ignore the couple ’ s stated or assumed contract regarding emotional and/or sexual exclusivity and become more engaged in in fi delity. 23 The microsystem of the ECSD not only includes information about individual and partner characteristics (bioecological sys- tem), but also might involve sexuality issues, including sexual desire, sexual interest, and sexual excitation. In fi delity engage- ment may be linked to interactions with a sexual partner, such as the partner ’ s hypoactive sexual desire or anorgasmia. 25 It also may be developed from very early interactions with parents, for example, an unfaithful or divorced parent. 26,27 Experiences within each microsystem will lead to all the personal scripts surrounding individual and couple sexual behaviors, such as sexual in fi delity. The mesosystem comprises the reciprocal interactions that take place among the microsystems within an individual ’ s life. 10 Although a couple is de fi ned as a union system, communica- tional interaction between 2 partners is affected not only by everyone ’ s partner, but also by other system interactions. This subsystem emphasizes surrounding interpersonal relationships. 17 The most frequent variables in a couple ’ s mesosystem are marital and sexual dissatisfaction; however, there have been few studies addressing quality, interaction, happiness, 28 instability, and con fl ict in a marital relationship with the same results. The exosystem includes a situation or institutions that affect an individual ’ s daily settings but are not part of the individual ’ s immediate environment. 10 The exosystem of the ECSD can include public debate and acceptance/rejection over in fi delity, as well as opportunities for it. Certain variables, such as social media, occupation, urban residence, home instability, social life, and travel, are classi fi ed as societal variables because they are theoretically related to in fi delity by creating an opportunity and a facilitative context for sexual or emotional in fi delity. 29 Oppor- tunity refers to the availability and willingness of the third per- son, as well as factors that facilitate secret contacts from the spouse. 30 The macrosystem of the ECSD comprises cultural and societal principles with broader in fl uences on couple ’ s system that lead to in fi delity. Traditional value systems condemn in fi delity, but these norms are changing. 31 Cultural beliefs and values of a country can also have a signi fi cantly direct or indirect effect on human behavior (eg, in fi delity) and determine what is considered right or wrong behavior within a society. 10 Today, the type, functions, and characteristics of marriage vary among cultures, and these can change over time. Consequently, social construc- tions about in fi delity are changing, making it important to un- derstand the social context of a new sexual behavior and its related factors. 32 The chronosystem of the ECSD consists of changes relating to time or throughout the lifecycle that in fl uence individuals and their environment. 33 For example, when a couple ’ s lives are shared and merged, their chronosystems are also shared and merged. The chronosystem continuously changes and evolves over time. Thus, the chronosystem of the ECSD refers to life events that either indirectly affect an individual ’ s desire and psychological processes to engage in in fi delity (eg, partner with an illness, partner ’ s suspected affair) or directly in fl uence his or her experience of in fi delity, such as divorce history, previous in fi delity, or sexual abuse. 9,34 e 37 We next describe the factors associated with engaging in in- fi delity, as conceptualized through Bronfenbrenner ’ s ecological systems theory. However, it is important to recognize that these factors are descriptive and do not completely characterize all the factors that might possibly in fl uence in fi delity engagement. Microsystems Numerous microsystems form throughout an individual ’ s life. However, based on the present systematic review, certain microsystems have been identi fi ed as signi fi cantly in fl uencing in fi delity engagement, including individual, partner, and parent characteristics. Individual Characteristics Individual characteristics include sociodemographic factors, psychological and biological factors, personality traits, sexual information, attitudes toward in fi delity, in fi delity experience, and alcohol consumption. Sociodemographic Factors. The closest level to the individ- ual is the microsystem that includes sociodemographic factors that can in fl uence processes in the individual ’ s immediate envi- ronment. Sociodemographic variables are mediators and may interact with the partner ’ s sociodemographic factors, such that whenever individual and relational factors overcome a person, the role of sociodemographic factors is diminished. Gender has been repeatedly related to in fi delity with men identi fi ed as more likely to engage in this behavior than wom- en. 34,36 e 41 Based on the ECSD, cultural issues and social norms responsible for sexual behaviors such as in fi delity lead to the acceptability of it in men and blame for it in women. 42 In the other hand, people are less likely to admit the behaviors that transgress social conventions. 43 In this regard, women may be more likely than men to underreport in fi delity, considering the J Sex Med 2019;16:1155 e 1169 In fi delity and Its Associated Factors 1159 social backlash that women receive compared with men for the same behavior. 44 Age 8,34,45 and education 19,36,37,46,47 were 2 of the weakest predictive factors for in fi delity, because the results of studies on age have been contradictory. The experiences, skills, sexual functions, and motivations of people vary at different ages, even if their immediate environment is the same. 16 Bronfenbrenner postulates that human behavior is in fl uenced by individuals and contexts, such that not everyone will experience them in identical fashion. 10 Experience with premarital sex, 48 childhood sexual abuse, 49 and motivation for in fi delity 50 are able to mediate the effect of age on in fi delity. Above all, it is necessary to pay attention to the age of the partner. Power and income are considered resource characteristics that increase in fi delity engagement. According to the ecological model, 2 people may have equal resource characteristics, such as high income or power, but their behavior (eg, in fi delity engagement) may be quite different; for example, if one is motivated to act and continue it and the other is not. 51 e 53 Psychological and Biological Factors Several mechanisms may plausibly account for the association between psychological distress, such as poor decision making under stress, 54 escape confrontation 55 increasing negative emotional ex- periences, and seeking social support, 56 and in fi delity. 57,58 Based on the ECSD, people who are anxious or depressed are more likely to engage in in fi delity if their spouse has no supportive role. Biological factors, such as high levels of follicle-stimulating hormone, 59 endogenous testosterone, 25 and heretical factors, 60,61 are known as risk factors for risk-taking behaviors, such as in fi delity. 62 The association between a committed relationship and reduced testos- terone levels in men con fi rms and extends previous research linking testosterone level with mating effort. 63 The effect of biology on sexuality can be described as a predisposing factor that in fl uences sexual interest, desire, and response of individuals 64 that predict a greater likelihood of in fi delity. 65 Personality Certain personality traits, such as neuroticism, have been identi fi ed as strong and consistent predictors of in fi delity in many studies. 20,66 e 73 In addition, other personality characteris- tics, including self-regulation, self-expansion, responsibility, self- esteem, and thoughtful decision making, have important roles in in fi delity behavior. 74 e 80 In fi delity behavior depends not only on the individual ’ s personality, but also on his or her partner ’ s personality. 16,81 Personality differences and interactions within the couple are important determining factors of in fi delity. Thus, high compatibility scores and similarity between partners in terms of personality are associated with higher levels of marital satisfaction 82 and lower rates of in fi delity. 67 Sexual Information. Sexual information includes previous sexual experience, propensity of sexual excitation, sexual attitudes, sexual interest, and age at fi rst intercourse. The rate of in fi delity is higher in people who have experienced sexual abuse 48,49,83,84 or premarital sex. 85 Dysfunctional patterns resulting from neglect or abuse in childhood, include those surrounding intimacy, emotional closeness, and building trust in romantic relationships, can lead to in fi delity 49 ; however, a sup- portive partner relationship can mitigate the effects of bad ex- periences in childhood. 86 Overall, a higher propensity for sexual excitation was associated with increased in fi delity. 3 Bancfort postulated that individuals with a high propensity for sexual excitation are more likely to engage in high-risk or otherwise problematic sexual behaviors. 87 In addition, individuals highly interested in sex might eschew sexual exclusivity and be more likely to have multiple partners because they expect greater pleasure from relations outside of marriage. 88 Such sexual attitudes as unrestricted sociosexual orientation and premarital sexual permissiveness are related to greater in fi delity. 66,89 e 92 These factors are a part of sexual value system that links a set of religious ideologies, liberal politics, and gender egalitarianism to premarital sexual permissiveness. A couple ’ s compatibility in a sexual values system is important for those who believe in an exclusive romantic relationship. Attitudes Toward In fi delity and In fi delity Experi- ence. Studies of the role of attitudes toward in fi delity and pre- vious in fi delity have shown a positive correlation between such variables and in fi delity. 35,48,79,93,94 Attitudes have the greatest impact on in fi delity behavior, being the key channel through which the intention engage in in fi delity is developed. These re- sults are not surprising, given that unfaithful individuals with more liberal sexual attitudes have a higher propensity of sexual excitation, 3 which is associated with increased in fi delity. Alcohol Consumption. Intoxication makes people more likely to be involved in extramarital sex. 45,85,95,96 Alcohol can affect marital life, given the strong associations between alcohol consumption and violence, negative interactions, and marital dissatisfaction, as well as some empirical evidence of positive effects. 97 A discrepancy between couples regarding alcohol con- sumption is also associated with in fi delity. Partner Characteristics An individual ’ s in fi delity behavior is considerably in fl uenced by his or her partner ’ s characteristics. Our fi ndings suggest that such characteristics as partner ’ s personality (as mentioned pre- viously), educational background, income, attractiveness, and sexual dysfunction are associated with engagement in in fi delity. Sociodemographic Characteristics (Income and Education). Income has a very complicated role in in fi delity engagement. More than money and income, it is a discrepancy in wealth levels that triggers in fi delity behavior. 19 However, a greater wealth index is associated with greater in fi delity only in men. 8,45,98 J Sex Med 2019;16:1155 e 1169 1160 Haseli et al The correlation between one ’ s own and partner ’ s income and education in in fi delity is nuanced; it likely re fl ects complex reciprocal interactions of social forces (eg, power, freedom, op- portunity) that are not easily captured by simple sociodemographic characteristics and that may be rapidly changing along with larger social changes. Attractiveness of Romantic Partner. Partner physical attractiveness as predictor of couples ’ satisfaction leads to a lower likelihood of in fi delity engagement. 3 Additionally, the attractive- ness of third person was one reason that leads to more likely to engage in in fi delity. 99 Based on the ecological model, skin color and physical appearance are a part of “ personal stimulus ” charac- teristics that act as an urgent stimulus to another person. This is why individuals engage in in fi delity when they fi nd other attractive men/women if their partner is not attractive. 99 Such a character may in fl uence initial interactions and sexual excitations. 100 Sexual Function and Dysfunction. Individuals with sexual dysfunction (eg, premature ejaculation, severely delayed ejacula- tion) are less prone to engage in in fi delity, 25 but those who partner has a problem with sexual function (eg, hypoactive sexual desire, anorgasmia) are at increased likelihood of engaging in in- fi delity. 25,101 Here the primary partner has an unmet sexual need that can increase the risk of in fi delity. On the other hand, good sexual functioning is associated with lower rates of in fi delity. 25,65,102 Parental Characteristics Parents represent a highly in fl uential microsystem in terms of sexual socialization. 17 Previous in fi delity, marital dissatisfaction, and divorce experience in parents are associated with in fi delity behavior in their children. 27 Parents ’ attitudes toward sexual behaviors are transmitted to their children, informing their be- liefs about sex and making them accustomed to in fi delity behavior. 103 Speci fi c behaviors at the parental level, such as parents ’ in fi delity, are fi rmly connected with offspring ’ s equiva- lent behavior. Interestingly, parents ’ satisfaction, con fl ict, and perceptions of in fi delity are also associated with offspring ’ s in- fi delity behavior. Mesosystem The mesosystem of the ECSD includes the couple ’ s relational variables, such as satisfaction, happiness, stability, con fl ict, and attachment styles. Marital Information Younger age at marriage 104 and fi rst intercourse 5,8,45,85 pre- dicted engagement in in fi delity. The signi fi cantly higher rate of in fi delity associated with teenage marriage may be rooted in the situations of these marriages, such as teen pregnancy, parental disapproval, and other issues. These interpretations are purely speculative, however. Cohabiting (vs married) status 105 and pregnancy 72,106,107 have been associated with higher rates of in fi delity. This fi nding sug- gests that it is cohabiting couples ’ lower investment in their unions, not their less conventional values, accounts for their higher risk of in fi delity. 108 Unmet sexual needs during pregnancy and personal beliefs about the effect of coitus on pregnancy can lead to declining coital frequency and decreased sexual satisfaction, which are sig- ni fi cant predictors of in fi delity during pregnancy. 109,110 Couple Relationship It has been well documented that marital satisfaction and happiness and good dyadic adjustment are associated with a lower rate of in fi delity and, conversely, marital dissatisfaction and insta- bility are associated with a higher rate of in fi delity. 36,40,67,111 e 114 Huston and Houts 115 presented 2 models, the perpetual prob- lems model and the disillusionment model, and provided some evidence in support of these models in demonstrating the deterio- ration of marital quality over the early years of marriage. Presum- ably, people who engage in in fi delity better exemplify a perpetual problems model, in which marital dissatisfaction is an important element. In this regard, Thompson 116 proposed a de fi cit model to clarify in fi delity, in which insuf fi ciencies in the primary relationship play central roles in hastening and sustaining in fi delity. He esti- mated that the quality of primary relationship (eg, low satisfaction, low sexual frequency) reliably accounts for 25% of variance in in fi delity. 116 Sexual Satisfaction There is a strong correlation between high sexual satisfaction and low in fi delity and vice versa. 69,70,102,113,117 Individual well- being (eg, pleasure, arousal, sexual excitement) and dyadic pro- cesses (eg, intimacy, expression of feelings) are 2 major dimensions of sexual satisfaction, such that people who experience a signi fi cant decline in sexual excitement may seek to reinforce their sexual satisfaction by engaging in the novel experience of sexual re- lationships outside of marriage. Moreover, a strong decline in in- timacy may be a stressful experience that leads to seeking out of sexual relationships outside of marriage to fi ll an emotional void related to their primary sexual relationship. 118 Attachment Style Insecure attachment styles have been associated with in fi delity. 7,21,69,119 e 122 According to Simpson et al, 123 “ attach- ment styles have clear and meaningful effects on actual behavior. ” The theory of adult attachment provides good examples of multidimensional perspectives on love. Insecurely attached people, who show high avoidance (fearful and dis- missing attachment styles), have different patterns of romantic preferences and behaviors than securely attached people. 124 They tend to show much less interest in romantic relationships, particularly ones in which a long-term commitment is neces- sary. 125 Consequently, partner attachment style is an important determinant of in fi delity (dis)engagement. 21 J Sex Med 2019;16:1155 e 1169 In fi delity and Its Associated Factors 1161 Exosystem Compared with studies examining microsystem or meso- system variables, fewer studies evaluated exosystem variables. Social Media People with social networking behaviors are more likely to engage in in fi delity. 71,88,126 e 128 High levels of social media use can damage an individual ’ s interpersonal relationships and thus provides a potential source of relationship con fl ict and dissatisfaction. 126 Social Life Social life (ie, spouse/partner-absent activities outside the regular work hours, including entertaining, dinner parties, calling on friends, and group travel) is associated with in fi delity in men. 89 A man who spends most of his leisure time with friends or others than his partner will encounter more opportunities for in fi delity. Concurrently, a partner who is left alone and feeling forgotten is also more likely to engage in in fi delity. Although loneliness has been suggested as a factor associated with in- fi delity, 114 this association remains speculative. Occupation People are more likely to engage in in fi delity with an opposite- sex coworker. 34 A workplace sex-mix has a greater correlation with divorce in women compared with men. 129 This fi nding may be rooted in reproductive biology; compared with women, men are more likely to engage in in fi delity rather than divorce a wife considered an unacceptable mate. 130 Macrosystems In the ECSD, religious and spiritual practices, race and ethnicity, and cultural factors are considered to constitute the macrosystem. Religion and Spirituality One of the most important factors in how the macrosystem affects in fi delity is through religion. Extramarital sexual activity is a prevalent concern for religious groups and traditions, all of which condemn it, although they differ in the strength of these norms. 131 However, in practice, the association between religion and in fi delity is inconsistent. Some studies have found that people with low levels of religiosity are less likely to engage in in fi delity 9,19,36,38,72,96,105 ; however, other studies have demon- strated no differences in rates of in fi delity as a function of reli- gious practice. 3,45,78 The powerful impact of religion may be related to several factors. Today, religious groups are being affected by globalization, which is diminishing their ability to maintain exclusive social networks that can restrict sexual behavior among their adherents. 9 Spiritual activities, such as prayer, sancti fi cation of mar- riage, 132,133 and the inspired word of God, 9 are associated with less in fi delity. When God is considered the third partner in marriage, the couple ’ s commitment to the relationship increases. God, through prayer for the spouse and the sancti fi cation of marriage, becomes an integral part of the marital relationship. In fact, spirituality provides stability through emphasizing a sus- tained and stable marriage. 134 Culture Cultural attitudes and beliefs about marriage, such as a bride price paid by the groom to the bride ’ s family, are associated with a lower rate of in fi delity in women but a higher rate of in fi delity in men, possibly related to the men ’ s sense of entitlement to engage in in fi delity. 135 Cultural beliefs and values of a country can have a considerable effect on human behaviors, including in fi delity. 10 Race and Ethnicity Although numerous studies have reported higher in fi delity be