Thanks for the welcomes and advice so far. It really helps to hear from others.
As for sharing a gf, what he wants is a relationship among 3 people, so a shared gf. If I were ever to have a poly relationship that is how I'd want it. I would want the love shared rather than him dating and me dating. I'm sure everyone is comfortable with different things, but that is the possibility for us.
Also, I do really trust my bf and we are very honest with each other. And yes, I am very happy when I am with him.