My bf used to quote Natural Born Killers on this, "Only love will kill the demon" or something. But people here are right: love does not mean being kind and accepting all the bullshit. You have to love the person, but you have to love yourself, too, and not let yourself be used. Love as strong as you can, become a tornado, and sweep 'em off their feet. Not everybody quits just because of the love. We cannot have unrealistic expectations about that.