Evolving together: Dynamic transactions of antagonistic and self-centered traits with couple relationships.

The reciprocal influence between personality and relationship experiences has been of considerable interest, but there is little research on the extent to which changes in relationship quality are shaped by changes in antagonistic or self-centered personality traits or, conversely, how changes in relationship quality impact these traits. In the present study, we examined how Machiavellianism, psychopathy, and narcissism are linked to key aspects of romantic relationships, including relationship satisfaction, commitment, reciprocity orientation, and verbal aggression. We used data from the German Family Panel (pairfam). The analyzed sample included N = 1,925 couples, with a mean age of 36.48 years (SD = 7.62) for anchor persons and 36.91 years (SD = 8.71) for their partners at the first measurement occasion. Across three waves of data collection, each 2 years apart, we applied extended bivariate latent change models. The results revealed both cross-sectional associations and correlated changes between the antagonistic/self-centered traits and relationship satisfaction, commitment, reciprocity orientation, and verbal aggression, with both actor and partner effects. Generally, higher levels in these traits were linked to lower relationship satisfaction and commitment, alongside higher reciprocity orientation and verbal aggression. Moreover, findings indicated a reciprocal influence between personality (change) and relationship (change), again involving both actor and partner effects, with narcissism showing the most consistent associations with relationship dynamics. The results are discussed in the context of existing literature on personality development in partner relationships. (PsycInfo Database Record (c) 2026 APA, all rights reserved).