Wow. I can't express the goodwill that I feel towards you right now for trying to honestly and seriously explore your options in your relationships. Your open mind and willingness to try new things gives me warm fuzzies, and I'm a pool of blood on the ground.
My two cents: love can happen a lot. It's not fun to have invested time in a relationship only to leave it, but sometimes it's not the right kind of relationship for you. You sound as if you open your emotional floodgates pretty easily, so letting someone else in shouldn't be too hard if you were to leave the people you're with.
Don't go breaking up with anyone because I said that sometimes relationships aren't right, though.
Take another long, hard look at things (as I'm sure you've already taken more than one) and decide whether
any of these people are giving you what you need on the emotional front. Then decide what action you're going to take to get what you need.
When you go to bed at night,
you are the person that you have to have made happy that day.