I don't fit into what a lot of people think of as bisexual, because I've never been in a relationship with another woman, I'm Catholic, and I'm pro-life. I also think that polyamory is something that can only lead to hurt feelings, jealousies, and general disaster.
I don't condemn people for whatever they do sexually, but I think that people should only have sex with someone they're in love with. A lot of people think this makes me too idealistic; however, I think the world needs idealists if anything's going to change.
It's possible to love two people at once, and you can't change who you love. However, having a romantic-sexual relationship with two people at once strikes me as rather selfish. It doesn't matter how "open" or "free" people claim they are; due to basic human nature, jealousies are going to develop. No one wants to be someone else's alternative option or second choice.