Another theory - that the trauma bond is analagous to how a rubber band works.

This is what I wrote in response to an abuse victim of narc abuse, on a different forum:

The trauma bond is like a rubber band. It expands when you feel like you need to and want to distance, and then it snaps you back suddenly because you want the good parts of them to come back and be permanent. With narcs, this is only a temporary "niceness" to pull you back in, make you want them again, and to keep you under his control so he can just tart to devalue, demean, and insult you all over again. Know and accept that this good side is only a facade - it is not real. It is not who he truly is, deep within. Deep within, he is a monster who does not have your best interests at heart or in mind. He is out to destroy, instead, and serve only his own needs. These acts of kindness are not truly for YOU - they are manipulations that only serve and benefit HIM in the end. These are very hard truths to believe or even accept. It's so hard to think that someone we think we love, is actually aiming to hurt us instead, to suit their own fragile ego that needs to feel power over and in control of their victim. Think of the trauma bond as analogous to a rubber band, and just realize that you have only been snapped back in, which soon will turn into the need to distance yet again. The cycle is not healthy. His anger and entire persona are not healthy. Narcissism is a mental illness, after all - a personality disorder. This translates to mean that this person, this man you believe loves you, is not mentally stable, emotionally healthy, and in fact, has little conscience in terms of the depth of the harm he inflicts upon YOU. The more you hammer reality into your head, the less likely the rubber band will continue to snap and reel you back in.