system
A chat on subreddit /r/NoStupidQuestions
human
Because of how society conditions each gender differently regarding heteronormative sex. Men are taught that sex is an accomplishment and if they get it, they've earned it, while women are taught that it's something they "give" to men they find worthy of it, so they better not give it to the wrong men or too many men or they're a "slut". This is reinforced by women generally having higher standards for men, and different criteria for sexual partners in general from men, which is in turn reinforced by the societal differences in moral lessons about sex stated above. It's a looping cycle of reinforcement that's slowly being weakened by evolving ideas regarding gender and sexuality spectra.
gpt
It might also be worth nothing that in the animal kingdom it is also the males trying to attract the females… makes me wonder if there is more to it than even societal expectations.

I know as a female 1 night stands tend to also be a bit disappointing… likelihood of getting off is a lot less.