Parentification, the reversal of parent-child roles, has lasting adverse consequences that extend into adulthood. Prior research suggests that adults exposed to parentification may oscillate between two maladaptive relational patterns—codependency and avoidance—yet the underlying mechanisms remain unclear. The present study examined whether shame proneness, guilt proneness, and rejection sensitivity mediate the link between parentification and these relational outcomes. A total of 290 young adults (ages 18-26; M = 21.47, SD = 2.08) completed standardized self-report measures, and data were analyzed using multiple mediation models. Results showed that shame proneness, guilt proneness, and rejection sensitivity partially mediated the association between parentification and codependency. In contrast, only rejection sensitivity fully mediated the association between parentification and relationship avoidance. Taken together, these findings provide new insight into the emotional pathways through which parentification shapes adult romantic relationships, extending knowledge on relational dysfunction and developmental risk, and highlighting the need for longitudinal and cross-cultural research.