I am thinking it's another example of the vast CH-asm between the sexes; most women I know, myself included, find that sexual attraction is the first thing to go when they begin to take leave of the relationship as a whole.
Jumping off your post, though, OBE;
The thought of having sex with someone whom I found repulsive is, well, repulsive. But I am sensing more and more that for men (generally speaking), they can still get their freak on with a woman they find heinous.
I really don't know. But I do think that Travis was still greatly pressured by his friends to not see Jodi. I don't think breaking up with her was a choice he made by himself. Which is why he hid his continued sexual relationship with her.
I think if you REALLY want to dump a girl, you stop schtupping her. Travis was very motivated and strong willed in every other aspect of his life. I just don't buy that because of his "maleness", he was some instinctual beast incapable of using the cautious good judgement we expect from women.
Buying in to that theory would also mean that a man is less culpable for marital infidelity than is his wife. Because, gee, men will just take free sex if it's offered. But a woman who does it is a faithless *advertiser censored*.
I find that offensive to both men and women.