LAUSR

Abstract The study examined the effects of similarity in the Dark Triad (DT) traits on women and men's relationship quality (RQ) by using profile similarity (PS) and polynomial regression analysis (PRA) as the methods for the assessment of partners' similarity. Participants were 100 young adult heterosexual dating couples. The effects of similarity in the DT traits on RQ were somewhat different depending on different methods used as well as whether we considered women or men's RQ. PRA showed that dissimilarity in psychopathy was related to lower women's RQ, while similarity at high levels of Machiavellianism to lower RQ in women and men. Additionally, women's RQ decreased more sharply when partners were similar at high levels of Machiavellianism. PS in narcissism was associated with higher RQ in women and men. This study suggests that different methods of assessment of (dis)similarity could add to the more thorough understanding of the associations between personality traits and relationship outcomes.