These responses are interesting.... I started off having threesomes with the "you only live once" idea and also assuming I would never end up with the boyfriend I was "experimenting" with girls with. Obviously, he was all for it. 6ish years later, we're married and I went through a process of,
"I'm straight but I have sex with women sometimes with my man" then
"I'm bi-curious, I like both sexs, emotionally and physcially but I prefer men" to
"I'm bi, I think if I was in a situation where we got a divorce (doubt that'll ever happen) I would try dating women too.
I think the older I get the more my mind changes about various things, but for now, we do just have threesomes with another female and it's part of our relationship and we love it.