Similarity within romantic couples forms one component of the formation and maintenance of relationships, meaning that, romantic partners’ views about themselves and the world are theorized to converge over time. We advance prior research on romantic couple similarities using cross-sectional or time-lagged designs, testing convergence with dyadic trajectories of change—how changes in one person relate to changes in their partner. Dyadic growth curve models assessed initial similarities, and longitudinal convergence, for 35 measures of well-being and individual differences in 171 mixed-gender couples from a national longitudinal study (the New Zealand Attitudes and Values Survey). Results indicated consistent average-level similarities between romantic partners, a few instances of short-term convergence in sociopolitical views, and the consistent pattern that changes in people occurred independently to their partners. Findings advance theory on romantic interdependence by emphasizing the perspective that romantic partners’ convergence occurs as subjective experience rather than externally measured unification.