I'm bisexual, and I know how difficult it can be to come out. We have to do it every time we strike up a new friendship - unless it's obvious by the fact that you wear a badge or something. It's complicated for me by the fact that I am married to a man, and so any coming-out that I do seems a bit theoretical, and to put a spotlight on the sexual aspect of my nature. Mostly I think it is partly cowardice on my part, and partly that the subject doesn't come up. If you are gay and in a relationship, you want to come out so you can talk about your partner. If you don't have a same-sex relationship, there's no occasion to mention it. I always challenge homophobia - maybe I should just do so more often by saying that I am bisexual. And then there's the inevitable assumption that bisexuals are "just greedy". That's not it - we just don't rule out the possibility of falling in love with someone of the same sex. I have increasingly come out to both straight and gay friends over the years (and they were accepting, whilst not necessarily knowing how to respond). I have had a few gay people assuming that bisexuals are really gay, just not prepared to let go of the hetero handrail; and of course there's always the jilted lover who has had a fling with a bisexual only to discover that they were also having a relationship with a member of the opposite sex as well. A few years ago I fell in love with a bisexual woman (and I think she felt the same way) but we never went any further than kissing because I was in a monogamous relationship. I've never had a long-term relationship with a woman, but I think that one could have been. I've had, erm, flings with other bisexual women.
Basically, I love people.