I'm not at all interested in a relationship right now, so when guys say shit like that and I find them physically attractive, I'm so pleased. I feel like me and her are on the same page.
Because being a guy isn't like being a woman. If you aren't born a Brad Pitt, or if you don't only have a group of slutty female friends, something like a text from a girl pursuing sex with you seems like one of those novelty moments that makes for a good story to tell down the road that makes you feel good about your life. The primal impulse to pursue new territory and taste the forbidden fruit, is something all people struggle with. Sexual attraction or attraction to the idea of sex, does not disappear with commitment. If anything being in a relationship probably heightens these emotions, perhaps twice as much if you're not with a woman who has a large sexual appetite (which is the case for a lot of guys... not all women are sexual). So when something good falls into your lap, even though you know the answer has to be "no" it feels good to bask in it and at least let it marinade. It's really not about hypocrisy, it's just about getting what little satisfaction out of a moment as possible, seeing as that's as far as it's ever going to go without breaking commitments or vows.