Objective Social anhedonia is a deficiency in the capacity to experience pleasure from social interactions. This study examined the implications of social anhedonia for romantic relationship functioning, including the association of social anhedonia with sentiments toward romantic partners that are central to relationship functioning (satisfaction, commitment, regard for the partner, and care for the partner's welfare) and analogous perceptions of the partner's sentiments. Method Data were collected from 281 participants who were involved in romantic relationships. Results Social anhedonia predicted less satisfaction, regard, and care, and these effects were independent of attachment insecurity and self‐esteem. In addition, social anhedonia had an indirect negative effect on commitment via attachment avoidance. Social anhedonia also predicted more negative perceptions of the partner's sentiments. Conclusions Results suggest that social anhedonia may undermine the functioning of romantic relationships by reducing positive sentiments toward partners and security in the partner's sentiments toward the self.