Why do some women beat up their husbands/boyfriends? Don't pretend it doesn't happen, I've seen it several times on friends and acquaintances of mine, the police and social services say that an awful lot of men don't report it, probably out of embarrassment?
Why do men and women do it, no idea; I've never had a desire to do it, and I've never been with a woman that does it.
I remember one of my friends, a plumber, he'd just knocked off work and we were talking, he'd just come back from a women's refuge, where he had to replace the hot water tank, again, because one of the women had taken a hammer to it, again, and that was the sort of thing she was doing at home before her husband cracked her? I think if I had been married to her, that may have even tried my patience. That woman obviously needed help and was in the wrong place because her old man wasn't bright enough and eventually he lashed out after she did that sort of thing at home, instead of saying, look love, we need to get you to the doctors.
I don't think the thing is as easy to explain as the psycho babblers would have us believe.