["Journal of Personality, EarlyView. ", "\nABSTRACT\n\nObjective\nNarcissism is often proposed to drive attraction early in relationships but ultimately leads to poor long‐term outcomes that are distressing to narcissistic individuals' partners. We examined changes in relationship satisfaction over a six‐year period as a function of narcissistic admiration and narcissistic rivalry.\n\n\nMethod\nData came from 5869 romantic dyads and a subsample of 533 early relationships within their first year. Participants were part of the German Family Panel (pairfam). Respondents completed the short form of the Narcissistic Admiration and Rivalry Questionnaire. For 6 years, both respondents and their partners completed a single‐item relationship satisfaction measure.\n\n\nResults\nBoth one's own and one's partner's narcissistic rivalry were associated with lower satisfaction in the full sample, but not the new relationships sample. Narcissistic admiration was not significantly associated with satisfaction. Contrary to predictions, neither partner's narcissism moderated relationship satisfaction changes in either sample.\n\n\nConclusions\nDespite its association with lower baseline satisfaction, narcissistic rivalry failed to moderate longitudinal changes in relationship satisfaction. These findings challenge the assumption of a linear cost to narcissism over time and highlight the need to investigate alternative time scales or heterogeneous relationship outcomes.\n\n"]