Some might love them to self-sacrifice, although I am skeptical. Most stay because they are afraid of guilt, being judged, etc. My husband did something really bad (granted, by accident, but knowing him, if he would have been more patient and generally had less of a superior attitude towards everyone else it may have been avoided). Many people knowing us think I am still by his side after what he did because I must love him. No. There might be some love left, but mostly what keeps me in this marriage is guilt and fear of the unknown. And naivity, yes. So...you don't know how these people you mention in your list really feel. Love is such a fluffy concept, it doesn't fly as an argument for me.