Based on sexual strategies theory, we predicted that men would be less likely to continue an imagined long-term relationship following a partner’s heterosexual affair compared to homosexual affair. For women, it was expected that both affair types would result in a low willingness to continue the relationship, but especially so for homosexual affairs. We further predicted that the interaction would remain independent of the following moderator variables: number of affair partners, number of instances of infidelity, and real infidelity experience. Participants (N = 718) were randomly assigned to read one of eight infidelity scenarios and estimate the likelihood that they would continue the relationship. Results confirmed all three predictions. A separate analysis of relationship outcomes following real infidelity experiences provided additional corroboration. These results support the conclusion that threats to paternity and threats of abandonment differentially motivate men and women to terminate relationships in response to a partner’s infidelity.