How is it possible for some str8 people to have gay sex? Because it happens. Sometimes its hard to come to terms with who you are because of the way others treat you. So, people try to push themselves into be the "norm" and this always ends badly.
I had sex with men and when I did I pictured having sex with a woman with a strap on. I did what I had to do, to keep up with my "wifely" duties because I believed since i was married it was my job to take care of my husbands needs. (turned out he was gay too)