Predictors of extradyadic sexual involvement in unmarried opposite-sex relationships.

Using a sample of unmarried individuals in opposite-sex romantic relationships that was representative of the United States (N = 933), the current study prospectively evaluated predictors of extradyadic sexual involvement (ESI) over 20 months (from 2007-2010). Data were collected with self-report questionnaires via U.S. mail. Participants were 18 to 35 years old, and 34.9% were male. Variables tested as predictors included involved-partner factors such as demographic characteristics, sexual history, and mental health, as well as relationship-related factors including communication, sexual dynamics, and aspects of commitment. Future ESI was significantly predicted by lower baseline relationship satisfaction, negative communication, aggression, lower dedication, absence of plans to marry, suspicion of partners' ESI, and partners' ESI. It was not predicted by sexual frequency, sexual dissatisfaction, or cohabitation status. Although more problems with alcohol use, more previous sex partners, and having parents who never married one another predicted future ESI, there were many involved-partner demographic factors that did not predict later ESI (e.g., gender, age, education, religiosity, having divorced parents, and having children). None of the results were moderated by gender. These results suggest that compared to demographic characteristics, relationship dynamics and negative interactions are more strongly predictive of future ESI. Implications for future research are discussed.