Research has shown that diverging romantic relationship outcomes of grandiose narcissism can be explained by differential associations of agentic and antagonistic aspects of narcissism. In this study, we wanted to further investigate the underlying mechanisms by examining how narcissists perceive daily situations with their partners. In an online diary, 171 couples reported on 1941 daily situations experienced together. Analyses revealed that agentic narcissism was positively and antagonistic narcissism was negatively related to daily relationship satisfaction. These effects were differentially linked through distinct situation perceptions: Agentic narcissism was positively linked with relationship satisfaction through perceiving daily situations as, for example, containing more romance, sexuality, and love, while antagonistic narcissism was negatively linked with relationship satisfaction through perceiving, for example, more threat, criticism, and accusation. Results are discussed in light of the Narcissistic Admiration and Rivalry Concept and with respect to person–situation transactions in romantic relationships.