[Extradyadic Sex and its Predictors in Homo- and Heterosexuals.]

Infidelity appears to be a common phenomenon. Although there are initially positive consequences for the unfaithful partner, it has negative impacts on individuals, the relationship and health in the long-term. How often are extradyadic sexual contacts indicated within a German sample? Which factors predict infidelity? Via Internet (n=1 899) socio-demographic, individual (attitudes towards infidelity, religiosity), relationship (global and emotional relationship satisfaction, length of primary relationship, sexual agreements), and contextual factors (opportunities) were surveyed. The results of the regression analysis on an 80% subsample (n=1 533) were cross-validated with the remaining 20% of the data (n=366). The analysis showed that 4% of lesbian women, 34% of gay men, 29% of heterosexual women and 49% of heterosexual men reported extra-dyadic sexual contacts. Sexual orientation and restrictive attitudes towards monogamy and infidelity were found to be significant predictors. Low global relationship satisfaction, longer duration of primary relationship, non-monogamous relationships, availability of alternative sexual partners and ways to conceal infidelity increased the likelihood of extradyadic involvement. Cross-validation with 20% of the data (n=366) confirmed the stability of the regression model. Future research should examine identified predictors using representative population-based data. Predictors should be considered in therapy.