Boyfriend and Facebook problem. What do you think?

I'm agreeing with the other poster, you've pretty much worked it out for yourself. He's dang ridiculous with his 'you just want to mark your territory', and to me, it seems like he's trying to make himself available to other girls. He also seems like a major douche, but that's just my opinion. I'd break up with him, if I were you, because you're not being irrational at all and he is. Trust is key in relationships, and if you can't trust him, it's time to go.