Trust, I really think they do it deliberately to hurt us. Do they know why they are doing it? Probably not. All they know, I think, is such and such will hurt us the most. That is an that, for some reason, their minds keep.
Part I think it is to feed the emotional drama. They are always trying to engage us and if we don’t, they get frustrated. When they do they may escalate their antics/actions or they may get to a point where they give up. Well, but maybe we get it and just don’t let them know we get it…or we get it and just don’t care...
Putting responsabillity elsewhere rather than on themselves is a thing they do. That helps them dealing with the stuff they make and justifying OW/OM or justify to OW/OM why they left us, etc.
I’m not a psychologist, but i guess how it may differ in cases of lower-level repeated emotional trauma from outright abuse is that on the first the person may not be aware that they suffered any trauma while on the second the abuse was obvious and very visible. So, maybe the way of processing things is different. Also, if you are not aware that you suffered trauma it may be harder to realise you are dealing with the effects of a traumatic experience?...
Sometimes good things fall apart so better things can fall together. (Marilyn Monroe)