So I'm seeing a girl and she has a boyfriend. We've had threesomes with him, and with my best friend, and we've both been with many people without an ounce of jealousy. I'm always happy for her when she has another person in her life. The other day I came to visit her with another good friend of mine, and they really hit it off. He has a gf, and they're sort of open, but it's always a train wreck, so he doesn't usually sleep with other people, so I didn't consider how it would make me feel, theres also a history of this guy getting girls I'm interested in. Anyway, they started to have something, and it just eats me alive. It's not just the idea of them sleeping together, I somehow feel like I just don't want this guy to be my meta. I love him to bits, he's one of my best friends, but somehow, I can't deal with this. The girl feels like it will ruin what we have if I push her not to be with him, which it probably will. The crazy thing is, I love how open we are, we're usually so happy for each other, and everything is great. Why can't I feel like that now? I also one almost slept with this friends gf, when we first met, but I didn't persue it cos it was obviously too much for them. This just sucks