Basic Trope: Despite having an active interest and desire for sex, a character is ultimately nothing less than chivalrous in his dealings with the opposite sex.
Straight: Bob is always ogling women, making lewd comments and flirting with Alice. However, when Alice comes to him during a time of great crisis, he refuses to take advantage of her when she's in a vulnerable state.
Lampshaded: "Thank you, Bob. That was really sweet of you. Especially for a guy who's always staring at my ass".
Invoked: Bob intentionally cultivates the impression of a sex-mad The Casanova because he got his heart broken once and blames his nice-guy persona; when push comes to shove, however, it's the nice guy who wins through.
Defied: Bob is up front with his chivalrous nature.
Discussed: "Bob might come across as a drooling, sex-mad neanderthal, but he's got Hidden Depths, Alice — you'll see".
Conversed: "Bob drools over every woman he sees. Why is he suddenly being so polite to Alice?"
Deconstructed: Alice seems to be in her time of need, and Bob refuses to take advantage of her, but this is a Batman Gambit by Alice, and she takes advantage of him.
However, this turns out to be for a good cause. The Big Bad wants Alice for himself, but he only wants her as a virgin. This saves her from the Big Bad and all is well.
The story has the moral, "Being proudly open with your sexuality and a vile depraved rapist are by no means the same thing".