I would not be surprised if those who suddenly "get in touch with" their homosexual side may have actually had those feelings all along, and were afraid to act on them because of the stigma associated with homosexuality - both in the past and the present. How many stories do you hear of men who desperately tried to live a straight life, even marrying and having children, while at the same time being in denial of their own desires?
If my SO decided that he had those sorts of feelings, I would be devastated, but I would send him on his way if he needed something he wasn't getting in our marriage/relationship. While "open" marriage sounds like an interesting idea, I don't think that it would work for me personally (I have a bit of a jealous streak).
I suspect the prevalence of HIV is not any greater in the homosexual community than in the straight community these days. Anyway know?
There's yet another stigma - HIV/AIDS is a "gay" disease...