The aim of my dissertation is to further enlighten the complex and dynamic interplay between personality and romantic relationships. In order to approach this aim, I pursue three lines of research and bundle them in three manuscripts. In the first manuscript, I rely on McAdams and Pals' (2006) conception of a three-layered personality. I shed light on the concurrent associations between the three major components consisting of personality traits, characteristic adaptations, and life narratives. Further, I investigate their impact on both partners’ life and relationship satisfaction with a particular focus on the yet understudied influence of the narrative layer. In the second manuscript, I consider the reciprocal interplay between personality and romantic relationships and investigate how romantic partners mutually shape their personality development. A prominent approach that is dedicated to assess personal growth in romantic relationships and that will be the cornerstone of this manuscript is the Michelangelo phenomenon (Rusbult, Finkel, & Kumashiro, 2009). Therein, I apply a life-span perspective by comparing the key components of the phenomenon between three generations. Moreover, I will account for the conceptual interdependence of romantic relationships and implement the phenomenon into the Actor-Partner Interdependence Model (Kenny, Kashy, & Cook, 2006), which is the prominent statistical model for analyzing dyadic relationships. In the third manuscript, I focus on relationship outcomes and review the most-cited relationship outcomes within the last 20 years of relationship research. The anchor of this sorting process is Deci and Ryan’s (2000) self-determination theory with the three basic needs of relatedness, autonomy and competence. Additionally to assorting, the aim is to provide a nuanced discussion that will lead into a more comprehensive understanding of relationship outcomes. In sum, my dissertation is envisaged to last over a period of three years. The present manuscripts will illuminate the complex and dynamic interplay between personality and romantic relationships by analyzing how components of personality are interrelated and differentially contribute to both partners’ relationship satisfaction (manuscript 1), by examining personality development through the lenses of life-span and dyadic research (manuscript 2), and by sorting relationship outcomes with regard to humans’ most elementary needs (manuscript 3).