A friend basically asked me this tonight. All I could say is that with this particular man treats everyone he loves badly, just look at how he treats his own child. He feels because he is in an intimate relationship with her, he need not be be courteous, kind or even polite anymore. He balances kindness with abuse, intimacy with rejection, and he has done this almost since the beginning of their relationship.
She seems to believes that if he really loved her, he would magically become a different person, like a fairy tale of some sort, that love is a magic pill.

For several years I have watched, listened and comforted her as their relationship goes through the same cycles over and over again. There are things she can do to change the patterns, which she does occasionally, but she can't be consistent, it is as if she does not value herself enough to hold him accountable. In many ways she rewards his bad behavior by giving him her complete attention whenever he does something. So many times when she thinks this guy is leaving her, she calls upset that her world is ending. He'll never leave her for real, why should he? She always goes back to him, and he gets what he wants. It has been very depressing and upsetting to watch.

UPDATE-11-07-She finally broke free of him, YEAH!!!