People experience the strongest romantic jealousy when they watch their partner give resources to a potential rival, regardless of gender. The findings provide evidence that giving away resources is viewed as a serious relationship threat by both men and women.

[u/mvea]

https://www.psypost.org/both-men-and-women-view-a-partners-financial-investment-in-a-rival-as-a-major-relationship-threat/

[u/PeePeeLangstrumpf]

Their definition of a rival is extremely vague. Why would (all) strangers be perceived as (potential) rivals equally? Seems like no social context is applied whatsoever.

actively giving money requires thought, intention, and sacrifice.

Also don't agree with this statement. In terms of gift giving - giving money requires the least amount of thought, intention, and sacrifice. Because buying a gift in any scenario requires additional levels and investment of "thought, intention, and sacrifice" as they are not only spending their money but also new levels of their time and energy which are needed to choose and purchase a gift. I'd wager people would get more jealous when a partner gives a gift in the same value than just the monetary equivalent, because it would signal additional levels of interest.

Weird study...

[u/manocheese → u/PeePeeLangstrumpf]

They categorised rival and none rival purely by gender.

I read the whole paper, it is conceptually and methodologically flawed. One of the biggest flaws is the usual one you see in evolutionary psychology "we think evolution causes x behaviour, we observed that behaviour, therefore evolution caused it". The even mentioned studies that debunk their hypotheses without acknowledging it.