Expected mindreading is the belief that romantic relationship partners should know each other’s needs and feelings without having to communicate them and is tied to poorer communication, greater conflict, and lower relational satisfaction. Despite associations with important interpersonal variables, no prior research has undertaken a dyadic approach to examine associations between expected mindreading and relationship quality. Given the interdependent nature of relationships, it is crucial to consider the influence of both partners. In the present cross-sectional online questionnaire study, 142 couples and 222 unpaired individuals in romantic relationships completed measures of expected mindreading, felt understanding, felt transparency, actual transparency, and relationship quality. I hypothesized that individuals higher in expected mindreading and their partners would report lower relationship quality (i.e., actor and partner effects) and that higher combined couple expected mindreading scores would be tied to lower relationship quality (i.e., shared vulnerability effect). I also predicted that felt understanding, felt transparency, actual transparency, and relationship improvement strategies would moderate the association between expected mindreading and relationship quality. As predicted, results of the couple sample Actor-Partner Interdependence Model revealed actor, partner, and shared vulnerability effects, with greater individual- and couple-level endorsement of expected mindreading tied to lower relationship quality for individuals and their partner. Supporting my prediction, felt understanding moderated the association between expected mindreading and relationship quality. For those higher in expected mindreading, relationship quality was somewhat protected from their dysfunctional belief when felt understanding was higher compared to lower. Contrary to my hypotheses, neither felt nor actual transparency moderated the association between expected mindreading and relationship quality. Results of the unpaired sample revealed an actor effect, with a moderate negative association between expected mindreading and relationship quality, but no significant interactions between expected mindreading and felt transparency, felt understanding, or relationship improvement strategies emerged. Findings underline the importance of considering dyadic effects and felt understanding in both research and clinical realms. The results suggest key implications for our understanding of expected mindreading and romantic relationship dynamics, as well as provide insight into treatment approaches to bolster relationship quality for those higher in this dysfunctional belief.