Whereas greater levels of intimacy have been shown to promote couples’ sexual well-being, recent theories suggest that satisfying sex is maintained via the capacity to encourage the partner’s individuality, while remaining intimately connected. Responses to capitalization attempts (i.e., the disclosure of a positive personal event) provide an opportunity to strengthen both the couple’s intimacy and each partner’s autonomy. Although responses to capitalization attempts are linked to couples’ greater relationship adjustment, very little is known about their relation to couples’ sexual well-being. The aim of this study was to examine the associations between self-reported, perceived, and observed responses to capitalization attempts and sexual satisfaction, sexual distress, and sexual function in 151 cohabiting couples who participated in a filmed discussion in the laboratory. They also completed self-report questionnaires pertaining to their responsiveness and to that of the partner during the discussion, as well as their sexual well-being. Results indicated that one’s higher levels of self-reported and partner-perceived active–constructive responses (enthusiasm/elaboration) during the discussion were associated with one’s own greater sexual satisfaction. Higher levels of perceived passive–constructive responses (quiet but interested) from one’s partner were associated with one’s own lower sexual satisfaction, and one’s higher levels of self-reported and perceived passive–destructive responses (lack of interest/self-focus) were associated with one’s own greater sexual distress. Finally, higher levels of observed active–destructive responses (undermines/denies the positive nature of the event) were associated with one’s own lower sexual function, while in women, they were associated with their lower sexual satisfaction. Findings contribute to a growing body of literature underscoring the importance of intimacy for sexual well-being in long-term relationships.