I'm bisexual and a woman. I've had a few relationships with women in the past and only one short relationship with a man. I'm an instinctive monogamist - it's never even occurred to me to want to fuck anyone else other than my partner whenever I've been in a committed relationship.
With age (I'm 30) I came to realize I actually have zero interest in going on dates or being in relationships with men ever again, and I've informed that to all my close friends and to my parents as well (yes). I cannot, however, call myself a lesbian, as I still like to fuck men from time to time. If a man I'm attracted to asks me out, I go full disclosure and tell him that no, I won't go out to dinner, because I don't go out with men, but we can have sex if he's interested. They are, of course, always interested. The very few times some of them tried to insist in making me participate in any kind of social interaction I've explained to them slowly and carefully that that's not what this is about: I just want dick - temporarily. What I'm really interested in is dating women and eventually marrying one (for those wondering, yes, I like sex with women better, and would take that over sex with men any day).
However, much to my disillusionment, that's not the M.O., by a long shot, of any of the bisexual women I've been in relationships with. They all turned out to be shady, closeted (one would introduce me as a "friend" even after she had proposed to me), manipulative, and yes, downright insane. They all ended up with men, and the ones who didn't remain closeted to this day. Moreover, they all have no qualms about breaking the hearts of lesbians in every possible way.
So, to hell with bisexual women (I know nothing about bisexual men). I'm not going down that road ever, ever again. I'm completely out and have been forever, everywhere, including at work, and I've never introduced any of my girlfriends as my "friends", to anyone (family included, and they all have a problem with my sexuality, by the way).
I'm sick and tired of the shadiness and overall dishonesty of bisexual women, all of the ones I've come into contact with, anyway. Fuck that, and fuck them. And if you're bisexual and think it's okay to fuck around on your partner, fuck you too.