Hey, everyone. Bisexual woman in a committed open relationship with a man, here.
I've never had a problem with anyone being less than accepting of my bisexuality--in fact, I think it was almost a point of attraction for a lot of people--but my partner and my's disinterest in sexual monogamy is a totally different ball of wax. A lot of our friends who don't flinch at someone's sexuality are a lot less comfortable when that same person wants to share it with people outside the relationship.
I think that my partner and I having sex outside of our relationship is actually very important for the health of our relationship as a whole. Sex with the same person, while comfortable and loving and occasionally very kinky, never really has that same breathless rush as having sex for the first or second time with someone you've been attracted to and never really thought you'd have sex with. And that I have someone to go home to afterward and share with, and that it makes both of us even more excited about each other, makes it all the better.
But I feel less sexy since I gained weight, and I know that's why I haven't really pursued anyone outside my partner--not because I'm not interested in anyone else, because I DEFINITELY am, but because I don't feel comfortable enough with myself to think I'd enjoy the pursuit.
But hey. I'M GETTING THERE.