I really don't subscribe to this assumption that simply because a girl is beautiful a man should automatically want her, and that if he rejects her he's either stupid or gay.
It suggests that all men are completely shallow and are only attracted by a shiny surface.
Evelyn is really beautiful, but it could be that he is not sexually attracted to her or her personality. She does seem a little immature at times, and I can't remember any remotely interesting conversations she's had for the entire time she's been in the house. He is a model, so must come in contact with "beautiful" women all the time, but maybe he likes someone with a little more depth?
As he has the character of a plank himself, maybe he needs someone more like Lateysha to have enough personality for both of them.