Besides intrapersonal psychological factors, interpersonal psychological factors are crucial for the development of mental health problems. Investigating the causal factors of these problems is difficult due to their limited manipulability in experimental settings. To address this problem, we propose to employ agent-based modeling (ABM), a cognitive modeling method used in various research fields. Our study aims to explore the dynamics of trait narcissism within a social context. We developed a model based on empirical findings for the underlying factors of grandiose narcissism as personality trait. Entitlement and the associated desire for popularity form the core of narcissism in the model. Narcissists employ two strategies, narcissistic admiration and rivalry, to achieve their goal. While effective in emergent or short-term situations, these strategies prove less efficient in enduring relationships. Because of the natural shift of emerging contacts to enduring relationships, once adaptive behavior becomes maladaptive, prompting narcissists to seek short-term situations by adjusting their social environment. By implementing the model as ABM, we examine the characteristics that are crucial for the development of grandiose narcissism, specifically emphasizing the role of social interactions. To validate our findings, we analyze the simulated data using social network analysis (SNA) and compare it with real-world SNA results. This exploration of underlying factors aims to discuss potential interventions that can be tested using ABM. Our approach demonstrates the applicability of ABM in psychological research, especially in studying both intrapersonal and interpersonal factors contributing to mental health problems.