It's inherently chauvanistic. Sorry, but thems the breaks. It's intertwined with the "white knight" concept. Admittedly my sci-fi/fantasy reading is not wide as it could but I never see this trope applied to female characters, or by women. It only comes from men, usually about a man, written for men.
EDIT: Actually no that's not quite true. It occurs regularly in shoujo manga, because then the girl gets to the be the one that tames the sexual deviant with her pure heart.
And honestly it's just as sexist there.
Wait what? White knight? IOkay, well, now you're switching gears entirely. I mean, he literally saved Fela from a fire and is actively working to comfort and help their local sewer's hobo. Kvothe isn't a 'nice guy' in that sense, he's literally a nice guy, who has done actual good deeds and didn't demand anything of that in return. Those things anybody would be attracted to.
But that's not even the situation for the vast majority of the female characters. Only Fela, Auri, and Mola know about those. Everyone else is just attracted to his hot bod and general charisma. How is that sexist?
You don't even need more fiction for this reference point. There are plenty of women who just want a hot, dashing guy to go and have sex with them. I don't even understand what your trying to get at here, that women don't have sexual desires?
I mean, just fill in this sentence for me here: it's sexist for a guy to have casual sex with other women while pining for one particular one because....?
Edit: To answer your question about this trope being applied to a woman, something like that happens with the love interest in the third book of the Gentlemen Bastard's series. Locke, the main character, pines ONLY for Sabetha, but while Sabetha also loves Locke, she has had sex with other dudes in their time away from each other out of horniness. Neither of them think of it as a big deal.
Edit2: In fact, I'm pretty sure Denna is an example herself. She wants Kvothe, but she has sex with other guys. Often for exploitative purposes sure, but nothing says that she'd save herself for Kvothe otherwise.