Ace was not happy in a relationship with you, he didn't have the same bond he should have with you in a healthy relationship. He wants to be just friends with benefits, (my idead and suggestion). I think you should stop using pity against Ace. It isn't wrong to want some sort of sympathy, but you just use it past the limits it should be used. I think it's best you don't keep Ace in the situation he is in with you, and just to expect the fact that he wants to be friends.