Have you ever heard of a thing called traumatic bonding? Although the post I made about it in the past was in reference to abuse, it might serve here as well:
"When a person, male or female, has suffered harsh or painful treatment over an extended period of time, he or she naturally feels a flood of love and gratitude toward anyone who brings relief...but in the situations of abuse, the rescuer and the tormentor are the same person..."
"You can end up feeling that the nightmare of his abusiveness is an experience that the two of you have shared and are escaping from together [when he is behaving - my comment]; a dangerous illusion that trauma can cause....this may be true, but the reason he seems to understand you well is that he has studied ways to manipulate your emotions and control your reactions. At times he may seem to grasp how badly he has hurt you, which can make you feel close to him, but it's another illusion; if he could really empathic about the pain he has caused, he would stop abusing you for good."
That gave me a lot of insight into some of my behaviors, anyway. Hope this helps. Be strong!