From the perspectives of interdependence theory and sociometer theory, we tested the hypothesis that greater costs of relationship loss lead to heightened sensitivity to rejection cues and to increased motivation to behave in more relationship-constructive ways. We conducted a questionnaire study in which 319 undergraduates listed activities they shared with their closest same-sex friend and indicated how they would feel and behave if they were rejected. As predicted, a greater amount of shared activities with a friend led individuals to experience stronger negative self-relevant feelings following imaginary rejection by that friend, which in turn generally promoted relationship-constructive behaviors (and inhibited relationship-destructive ones). The results suggest that state self-esteem effectively functions as a relationship maintenance mechanism.