Why didn't he want to sleep with her? (Spoilers)

She wanted companionship. She was lonely. When he realizes he was getting locked in, he said something to the effect, "if you think this is going to get me in bed with you, then you're wrong." Which implies that he's been holding out. Is it realistic, especially in the free love decade, that a dude would turn down a lonely housewife? Especially one that has been so nice as to feed you, bathe you, and gave you a place to sleep? It couldn't have been a morality thing because he had no problems getting in bed with the hooker.

I really felt sorry for her. But if the "boy" was purposely using her, seducing, teasing, holding out, etc. then man, he must have regretted it at the end. There was no need to drive this lady insane, to the point of renting and murdering a hooker. Of course he didn't know that would happen, but in hindsight, I bet he wished to do things differently.