Jealousy decreases as rival number increases: Preregistered tests differentiating between functional and intuitive...

Intuition and theory alike suggest that romantic jealousy should track the "amount" of cheating, with jealousy increasing as the number of affair partners increases. A functional account-conceptualizing romantic jealousy as an adaptation for managing the relationship-relevant fitness threats posed by romantic rivals-suggests instead that jealousy should track the implications entailed by infidelity. In this view, repeated infidelity involving a single affair partner may imply greater emotional involvement than the same number of encounters divided across multiple partners. We tested between these accounts using two preregistered studies of U.S.-residing CloudResearch participants (N = 1,318) conducted in 2023. In Experiment 1, using a repeated-measures design, jealousy appeared to decrease as the number of affair partners increased-despite the total number of sexual encounters remaining constant across scenarios. In Experiment 2, we replicated this effect using a between-subjects design and found evidence for the potential mediating role of emotional attachment concerns. Participants in Experiment 2 also rated one-off encounters across multiple affair partners as "more" cheating than the same number of encounters in relation to a single affair partner, suggesting greater jealousy in response to "less" cheating. Importantly, anger at one's partner did not significantly differ across scenarios, indicating some degree of specificity to jealousy. These seemingly paradoxical findings support functional accounts of romantic jealousy and highlight the utility of adaptationist approaches to affective science. (PsycInfo Database Record (c) 2026 APA, all rights reserved).