wow, that's fascinating. There was an Australian prime minister with a similar look to Obama - Paul Keating - I just went and had a look after reading your post and there are lots of articles saying he's gay too. He had a nice wife - I now see they are divorced.
I too cannot imagine what it would be like to be sexually attracted to a woman's body. It's like my mind just won't go there. And I can only imagine it is the same for people who are same sex attracted - their mind doesn't go there either, with the opposite sex.
I think you are right about the compartmentalisation - that's how they do it.
It is crushing for the straight in a MOM.