The academic consensus is that one’s number of lifetime partners is a strong predictor of infidelity: “A truism in psychology is that the best predictor of future behavior is past behavior. This is no less true in the realm of sexual behavior. Indeed, one of the strongest predictors of marital infidelity is one’s number of prior sex partners. Deception about past sexual promiscuity would have inflicted greater costs, on average, on men than on women” (source). After interviewing thousands of women, Whisman and Snyder found a 7 to 13% increase in the likelihood of infidelity per additional sexual partner depending on their mode of interview (source). Hughes and Gallup determined “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)” (source). Cherkas et al. found that infidelity and promiscuity are both under moderate genetic influence in women, and that “nearly half the genes impacting on infidelity also affect number of sexual partners.” (source). Pinto and Arantes found that sexual promiscuity is not only strongly related to sexual infidelity but that it is also strongly related to emotional infidelity (source). Barta and Keene wrote that “[i]ndividuals exhibiting sexually permissive attitudes and those who have had a high number of past sexual relationships are more likely to engage in infidelity (Feldman & Cauffman, 1999). In a study of supposedly exclusive dating couples, it was found that individuals exhibiting an ‘unrestricted’ sociosexual orientation (SO) were significantly more likely to pursue extra-pair involvement (Seal, Agostinelli, & Hannett, 1994)” (source). An unrestricted sociosexual (promiscuous) orientation is associated with low commitment and a desire for new, attractive partners (source). FSU researchers Fincham and May in an effort to summarize the current state of research on the prediction of infidelity, listed “[g]reater number of sex partners before marriage predicts infidelity as one of the individual factors that predict infidelity," further saying, “[a]s 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” (source).

“Contrary to conventional wisdom, when it comes to sex, less experience is better, at least for the marriage,” wrote W. Bradford Wilcox, Professor of Sociology at the University of Virginia (source). A greater number of previous partners is linked to low marital satisfaction and divorce (source). Using CDC National Survey of Family Growth (NSFG) data collected in 2002, 2006-2010, and 2011-2013, University of Utah professor Nicholas Wolfinger found that women with 10 or more partners were the most likely to divorce, with the highest 5-year year divorce rates (33% vs. 20% for normal people) (source). Busby et al. set out to determine whether the number of sexual partners was associated with poor relationship outcomes while controlling for relationship length, education, race, income, age, and religiosity. The results, using a sample of 2,654 married individuals, indicated that the number of sexual partners was associated with lower levels of sexual quality, communication, and relationship stability (source). University of Denver researchers Rhoades and Stanley reported “that the more sexual partners a woman had had before marriage, the less happy she reported her marriage to be” (source). Sarah Estelle, a Hope College economics professor, applied econometric methods to separately identify the effects of religion, age, education, and cohabitation on the Female Respondent File of the 2006-2010 National Survey of Family Growth, which provides data on the past intimate relationships of over 12,000 women. Her findings suggest a significant positive correlation between the number of premarital sexual partners on the likelihood of divorce (source).