Factors found to facilitate infidelity
Number of sex partners: Greater number of sex partners before marriage predicts infidelity
As might be expected, attitudes toward infidelity specifically, permissive attitudes toward sex more generally and a greater willingness to have casual sex and to engage in sex without closeness, commitment or love (i.e., a more unrestricted sociosexual orientation) are also reliably related to infidelity (pg.71)
Fincham, F. D., & May, R. W. (2017). Infidelity in romantic relationships. Current opinion in psychology, 13, 70–74.
Men apparently assess and evaluate levels of sexual activity by a woman prior to long-term commitment—behavior that would have been observable or known through social reputation in the small-group lifestyles of our ancestors. Past behavior is a good predictor of future behavior, and having a large number of sex partners prior to marriage is a statistical predictor of infidelity after marriage (pg.92)
Buss, D. M., & Schmitt, D. P. (2019). Mate preferences and their behavioral manifestations. Annual Review of Psychology, 70, 77–110.
the odds ratio of 1.13 for lifetime sexual partners obtained with the face-to-face mode of interview indicates that the probability of infidelity increased by 13% for every additional lifetime sexual partner (pg.150)
Whisman, M. A., & Snyder, D. K. (2007). Sexual infidelity in a national survey of American women: Differences in prevalence and correlates as a function of method of assessment. Journal of Family Psychology, 21(2), 147–154.
promiscuity is in fact a good predictor of infidelity. Indeed, promiscuity among females accounted for almost twice as much variance in infidelity (r2 = .45) as it did for males (r2 = .25). (pg.177)
Hughes, S. M., & Gallup, G. G., Jr. (2003). Sex differences in morphological predictors of sexual behavior: Shoulder to hip and waist to hip ratios. Evolution and Human Behavior, 24(3), 173–178.
Each additional sex partner between age 18 and the first union increased the net odds of infidelity by 1% (pg.56)
Treas, J., & Giesen, D. (2000). Sexual Infidelity Among Married and Cohabiting Americans. Journal of Marriage and Family, 62(1), 48–60.
Sexual promiscuity was significantly positively correlated with emotional promiscuity [r(356) = .261, p < .001], as well with sexual infidelity [r(323) = .595, p < .001] and emotional infidelity [r(323) = .676, p < .001] (pg.390)
Pinto, R., & Arantes, J. (2017). The Relationship between Sexual and Emotional Promiscuity and Infidelity. Athens Journal of Social Sciences, 4(4), 385–398.
Regarding other sexual behaviors, we examined whether number of prior sex partners and viewing pornography predicted ESI. As has been found in prior research (Feldman & Cauffman, 1999; Treas & Giesen, 2000), having had more prior sex partners predicted future ESI (pg.12)
Maddox Shaw, A. M., Rhoades, G. K., Allen, E. S., Stanley, S. M., & Markman, H. J. (2013). Predictors of Extradyadic Sexual Involvement in Unmarried Opposite-Sex Relationships. Journal of Sex Research, 50(6), 598–610.
When compared with their peers who report fewer partners, those who self-report 20 or more in their lifetime are:
Twice as likely to have ever been divorced (50 percent vs. 27 percent)
Three times as likely to have cheated while married
Substantially less happy with life (p < 0.05) (pg.88-89)
Regnerus, M. (2017). Cheap sex: The transformation of men, marriage, and monogamy.
women who had more experience with short-term relationships in the past (i.e., those with high Behavior facet scores) were more likely to have multiple sexual partners and unstable relationships in the future. The behaviorally expressed level of sociosexuality thus seems to be a fairly stable personal characteristic. (pg.1131)
Penke, L., & Asendorpf, J. B. (2008). Beyond global sociosexual orientations: a more differentiated look at sociosexuality and its effects on courtship and romantic relationships. Journal of Personality and Social Psychology, 95(5), 1113–1135.
Generally speaking, respondents who report extensive premarital sexual experience report extensive extramarital activity. Measures of the locus of first intercourse and number of premarital partners show positive associations with (1) rating one's marriage as less happy than average, (2) the number of different extramarital partners, and (3) the intention to participate in mate-swapping activities. (pg.221-222)
Athanasiou, R., & Sarkin, R. (1974). Premarital sexual behavior and postmarital adjustment. Archives of Sexual Behavior, 3(3), 207–225.
The findings from this study demonstrate that the number of sexual partners participants had was negatively associated with sexual quality, communication, and relationship stability, and for one age cohort relationship satisfaction, even when controlling for a wide range of variables including education, religiosity, and relationship length. (pg.715)
Busby, D. M., Willoughby, B. J., & Carroll, J. S. (2013). Sowing wild oats: Valuable experience or a field full of weeds? Personal Relationships, 20(4), 706–718.
As predicted, such factors as sexual permissiveness, an avoidant romantic style, number of romantic relationships, and early onset of sexual intercourse were all correlated with a higher incidence of betrayal behaviors. These factors are likely to promote sexual activity with a larger number of partners, which, in turn, increases the chance that betrayal will occur. (pg.247)
Feldman, S. S., & Cauffman, E. (1999). Your cheatin' heart: Attitudes, behaviors, and correlates of sexual betrayal in late adolescents. Journal of Research on Adolescence, 9(3), 227–252.
There was a strong association between number of sexual partners and having an STD: those women with 5 or more sexual partners were 8 times more likely to report having an STD than those with only 1 partner, even after adjusting for age at first intercourse
Joffe, G. P., Foxman, B., Schmidt, A. J., Farris, K. B., Carter, R. J., Neumann, S., Tolo, K. A., & Walters, A. M. (1992). Multiple partners and partner choice as risk factors for sexually transmitted disease among female college students. Sexually transmitted diseases, 19(5), 272–278.
An indicator of whether or not the respondent has had previous sex partners is included and identifies the number of male sex partners the woman had previous to her relationship with her current primary partner… A history of numerous sex partners indicates a pattern or habit of sexual behavior that we expect will negatively influence sexual exclusivity in the current relationship. (pg.37)
Having previous sexual partners greatly increased the likelihood that a woman would have a secondary sex partner. In particular, a woman with 4 or more male sex partners prior to her primary relationship was about 8.5 times more likely to have a secondary sex partnerthan a woman with no previous sex partners… Having previous sex partners also increased the likelihood that dating and married women would have secondary sex partners. In particular, married women with 4 or more previous partners were 20 times more likely to have secondary sex partners than married women with no previous sex partners (pg.41)
Forste, R., & Tanfer, K. (1996). Sexual exclusivity among dating, cohabiting, and married women. Journal of Marriage and the Family, 58(1), 33–47.