Although romantic couples can use communication to help one another lose weight and maintain weight loss, the effect of weight loss on partner interaction is less understood. However, an examination of the interpersonal context in which partners manage their weight is important to help partners negotiate their weight, their relationship, and the U.S. obesity epidemic. Guided by systems theory, this study explored partners' perceptions of post-weight-loss interaction in relationships in which one partner lost weight and the other did not. Through qualitative questionnaires of 42 adults (21 romantic couples), the dyadic investigation revealed that while losing weight resulted in positive interaction for many partners (e.g., engaging in a shared healthy lifestyle), shedding weight also yielded some negative consequences (e.g., non-weight-loss partner criticism). The extent to which partners embraced new weight management rules and patterns largely influenced post-weight-loss communication and behavior.