Wired for Cognitive Jealousy? Unveiling the Stability Within and Fluctuations Between Relationships

ABSTRACT Cognitive jealousy, which involves thoughts and suspicions of a partner's infidelity, is linked to various negative outcomes. Yet, little is known about how it fluctuates over time or across different relationships. This longitudinal study examined 891 young, unmarried adults in romantic relationships over 5 years (11 assessment points), capturing 1507 total relationships. About 42% of participants reported being in more than one relationship during the study period. The study examined how cognitive jealousy varies within individuals, across different relationships, in relation to individual traits such as neuroticism, attachment anxiety, and gender, and in relation to experiences of extradyadic sexual involvement (either self‐ or partner‐reported). Results showed that while 28.2% of the variance in cognitive jealousy was due to differences between individuals, the largest proportion (39.8%) was due to differences between relationships. Within a particular relationship, initial levels of cognitive jealousy remained relatively stable over time. Higher levels of neuroticism, attachment anxiety, and experiences of extradyadic sexual involvement (both self‐ and partner‐reported) were associated with greater cognitive jealousy. Men reported higher initial levels of cognitive jealousy than women. These findings suggest that relationship‐specific dynamics as well as individual differences play a crucial role in the experience of cognitive jealousy.