I do not want you to get bored with my own story, but I think I had a similar case with my wife. The one that I know today was not the one I got married with. In my opinion she was completely masked before. I couldn´t see her real personality.
Although this is tough stuff to cope with it has something positive: Now I am looking with open eyes who the other person is.
Trust IS necessary for a relation, and for no relation exists a guarantee. It will always be a risk.

"I could have missed the pain, but I'd of had to miss... the dance"

Well most of problem exists within myself really. I got to be too much of a pain in the ass. My nagging got the best of me. Unfortunatly, for me I learned my lesson too late he gave up on me. I can't say I blame him I really had no reason to treat him the way I did. A person can only tolerate so much bull before they walk.