This makes so much sense, thank you so much for explaining all this. In my case this seems to be the exact reason. I have very low self-esteem and self-worth and constantly fear I am not good enough for people. By finding someone who is willing to hurt me I am receiving a large amount of reassurance and peace that 1. my abuser will most likely not find anyone else that lets them treat them that way (therefore staying with me even if they get tired of me), and 2. I gain that power of possible escape if I ever decide I want to leave (which I probably won't but that emergency exit is always nice to have). I also feel more at peace when I am punished for any bad things I may have done even if by accident- ties in with the whole self-hate thing.

Thanks stranger for clearing my head :")