New research from the journal Evolution and Human Behavior reports that both men and women feel the most intense romantic jealousy when they see a partner give money to a potential rival. The study suggests that active financial investment in someone else is perceived as a serious threat to the relationship.
The findings challenge some long-held assumptions from evolutionary psychology that men and women react very differently to specific jealousy triggers. Instead, the results show a strong shared response to resource loss, with gender differences appearing only in more subtle ways.
Testing Jealousy With Real Money
The research team, led by professor Ana María Fernández of the University of Santiago de Chile, wanted to move beyond hypothetical cheating scenarios. Traditional studies typically ask people to imagine a partner’s sexual or emotional infidelity and then compare which is more upsetting.
To create a more realistic setting, the scientists used an economic game with real money and real couples. They reasoned that concrete financial choices could mimic the evolutionary threats of lost resources and mate poaching while still being ethically acceptable in a lab.
Mate poaching, in this context, describes attempts to attract someone already in a committed relationship. By framing the rival as an opposite-sex stranger, the researchers could examine how participants reacted when their partner seemed to favor this outsider.
How The Experiment Was Designed
The study recruited 79 heterosexual couples, for a total of 158 participants, all in relationships of at least six months. On average, they were about 30 years old and came to the lab together, but were seated apart behind a partition to avoid direct communication.
Participants played a modified version of the dictator game, a classic task in experimental economics in which one person decides how to divide a sum of money. Each person believed they were playing online with their partner and an unfamiliar opposite-sex individual.
In an investment scenario, the partner appeared to give 75 percent of the money to the rival and only 25 percent to the participant. In a receiving scenario, the partner appeared to accept a large amount of money from the rival. After each round, participants rated how jealous they felt on a 1 to 5 scale.
Giving Resources Sparks Strongest Jealousy
The data showed that the investment scenario produced the highest levels of jealousy for both men and women. Watching a partner allocate more resources to a stranger than to themselves was consistently rated as highly threatening.
According to Fernández, this pattern suggests that people interpret a partner’s deliberate financial sacrifice for someone else as a powerful sign of shifting loyalties. Giving money requires intention and cost, which participants seemed to read as emotional or relational investment.
By contrast, the receiving scenario did not produce the strong male-specific jealousy effect that evolutionary theory might predict. Men and women reported relatively modest and similar jealousy when their partner merely accepted money from a rival.
Why Receiving Money Mattered Less
The researchers argue that passively receiving money may not clearly signal romantic or sexual interest. A partner could accept resources simply to gain a free benefit without any intention of pursuing the other person.
This ambiguity may explain why jealousy levels in the receiving condition were weaker and less differentiated by gender. The signal of betrayal is less direct than when a partner chooses to give money away at a personal cost.
Control scenarios further strengthened this interpretation. When participants watched strangers exchange money, jealousy stayed lower, indicating that the most intense reactions were tied specifically to threats against their own relationship.
Subtle Gender Differences Emerge
Although the main reaction to partner investment in a rival was similar across genders, the researchers did detect a more nuanced difference in the control conditions. Women reported jealousy even when observing a committed man, not their own partner, giving money to a single woman.
This pattern suggests that women may be more globally attuned to the way men distribute resources, treating such behavior as a broader warning sign. Men in the study did not show the same level of generalized concern about strangers’ allocation choices.
Overall, the findings still align partially with evolutionary expectations that resource allocation carries particular weight for women. However, the dominant result is that both sexes strongly react when their own partner actively supports a rival.
Role Of Personality And Attachment
To understand why some people reacted more strongly than others, the team measured traits such as digital jealousy, attachment anxiety and attachment avoidance. Digital jealousy captures anxiety over a partner’s online interactions, such as social media activity or messaging.
Attachment anxiety reflects a fear of abandonment and a strong need for reassurance, while attachment avoidance involves emotional distancing and reluctance to depend on others. These characteristics are known to shape relationship behavior and conflict.
Participants who scored higher in digital jealousy and attachment anxiety reported stronger jealousy across nearly all scenarios. This suggests that personality and past relationship experiences significantly amplify emotional responses to perceived threats.
Limitations And Future Directions
The authors acknowledge several limitations. The lab-based setting, modest sums of money and brief exposure cannot fully replicate the emotional intensity of real-world infidelity or long-term financial betrayal.
There is also the possibility of social desirability bias, as participants might soften their reported jealousy to appear more composed. Additionally, the sample skewed toward younger, educated, heterosexual couples, limiting how broadly the findings can be generalized.
Fernández and colleagues plan to refine the experimental conditions, especially scenarios in which the partner receives resources from a rival. They aim to test whether this aspect of male jealousy can be modeled more clearly in future economic game designs.
Long-term studies tracking couples over months or years could also help reveal how jealousy responses evolve as relationships become more stable or as life circumstances change. Such work could deepen understanding of how resource allocation, trust and insecurity interact over time.
The findings provide a fresh look at how modern couples respond to subtle but telling cues of financial loyalty and potential betrayal.
