1) Kids/babies have one big job while growing up. They have to figure out how the world works. So they try to understand and make sense out of what they encounter and see. One of the big ways they do that is to swallow the values and beliefs that their families, teachers and society tell them about being an adult. The good kid who downloaded all the programming about who he was supposed to be in life is typical of a man who comes out late in life. Not being a questioning or introspective type of guy, he will either stumble over a guy that he falls in love with, or have a mid-life-like crisis. It will be at this point in his life that he finally figures out that he is unhappy. Suddenly, his life will not be fulfilling, and it is then that he really starts to search inside of himself and starts the process where he hopefully will figure out what is missing.
2) Some men acknowledge that they have had feelings for other boys and men while growing up, may have even had several sexual experiences, but feel that they cannot still be loved and be gay. They may continue to have sex on the side or not, but they feels like imposters as they act and do what is expected of them, even as they die inside.
3) Another possibility is that, as a boy, he was sexually abused. Whether he identified what happened as abuse or not, he uses those feelings as the basis for the belief that he would not be having those feelings towards men if it had not happened to him. This man is deeply ashamed and full of self-loathing. He desperately wants to be normal, and is angry about what was done to him as child and how it is keeping him from feeling/being normal.
4) Any and all of the above maybe tied to a religious belief that homosexuality is wrong. A common part of the self-hatred that makes up the core of how a gay man or boy may see himself is due to buying into the belief system that who one is, or what one does, is bad. While religion can and does play a positive role in many people’s lives, when a religion tells its believers to hate themselves for being who they are, it is criminal, and creates unnecessary pain in the world.