MARK WHISMAN

Although extradyadic sex has been repeatedly shown to be inversely associated with relationship quality, researchers have rarely evaluated partners' beliefs (or suspicions) of such behavior and the degree to which relationship quality varies as a function of suspected extradyadic sex. This study examined, in a United States probability sample of couples (National Couples Survey; N = 236 couples), the (a) prevalence of cross‐tabulations of wives' and husbands' reports of their own history of extramarital sex (i.e., sexual intercourse) and their beliefs about their partner's history of extramarital sex having ever occurred in the couple's relationship, and (b) associations between reported and suspected extramarital sex and current relationship satisfaction. The prevalence of different combinations of spouses' reported history of their own extramarital sex and suspicions of their partner's history of extramarital sex are presented. Results indicated that both spouses' reports of their own history of and their suspicion of their partner's history of extramarital sex were significantly and inversely associated with wives' and husbands' relationship satisfaction. These findings underscore the importance of examining not only respondents' report of their own extramarital sexual involvement but also their beliefs about their partner's extramarital sexual involvement in future research on relationship and individual functioning outcomes associated with extramarital sex.