Oly, this is a terrible thing to say, but I have a tiny gut feeling, reading your posts, that your wife is saying some of the things partners say when they are trying to leave a relationship without having to suffer the guilt of being the one who broke the relationship up.
I could be very far wrong... and my experience is very different from yours. For one thing, I've only ever been in one poly relationship, and it was brief. Second, I'm a straight female, and I've only ever seen this kind of "wriggling away" behaviour in men, and I've always thought of it as a male behaviour.
I hope I'm wrong. But be gentle with your OWN heart, not just hers (you sound very solicitous of her). Welcome to our board.
Leelee, all alone.