Need fulfillment has been found to be associated with numerous positive relationship outcomes, but its impact on stay–leave behavior is less clear. In the current study, we considered whether the fulfillment of different needs might differentially affect stay–leave behavior. We distinguished between needs that are personal in nature and those that are relational in nature. Central to our theoretical analysis is the interdependence-based contention that the fulfillment of different kinds of needs provides diagnostic information regarding a partner’s motives and intentions regarding a relationship. Using two-wave longitudinal data obtained from romantically involved participants, we tested the relative fit of two alternative models that specified the associations between the fulfillment of different kinds of needs, commitment, and stay–leave behavior. Consistent with an interdependence approach, we found that the influence of the fulfillment of personal needs on stay–leave behavior was mediated by commitment, whereas the fulfillment of relational needs directly influenced stay–leave behavior. Implications for relationship functioning are considered
