There's a theory that we are all bisexuals. We just fall on different spots on the scale between straight and homosexual (except folks who are asexual, I guess). That being said, the "strength" of the character's "gayness" would likely affect his ability to go against his true desires. Just like if you're essentially straight for all intents and purposes, but bi-curious, it might be easier to force yourself into a homosexual relationship whereas if you're at the extreme end of "straight" on the straight-gay-scale, it would be much harder. Granted, this hasn't much to do with reasons for a gay man to go straight but it might play some part on how credible it is of him to (try to) accomplish such a feat as well as his chances of success/failure. Just a thought...
Your answers I think lie with that sentence. Wanting to be straight isn't about conforming or fitting in, that's all rubbish. The desire comes from the feeling of self hatred. It's really that simple. If you want to write that type of character, create past experiences in which he displayed signs of being gay, was riduculed for it, then in reflection, he punished himself for showing it. Or you can have him reflect about how his family and friends would react if he were to come out. What types of things would his parent's say? How would their attitudes change? It doesn't matter if the consequences aren't serious to us or the reader, it's all about how Ethan will twist them negatively on himself to justify the feeling that being straight man is better. If you're planning to have a character reversal or whatever it's called, you have to make him love himself. He has to realize everyone around him isn't going to ridicule him for being gay. The important thing to remember is Ethan should not be aware that self loathing is the core reason he wants to be straight. He tries to figure himself out, but he only stratches the surface. That is part of his struggle. Only when you want him to change as a character should he discover that reason. So I'm rambling. I hope that helped in some way.
