A lot of domestic violence ends badly because police actions ensured that it would. E.g. instead of leaving the bastard the woman develops a sort of codependent relation with local cops so that every busted lip she suffers means the bastard gets a tag-team beatdown from everyone on duty. Nightly entertainment for the whole neighborhood!

I'm no fan of wife-beaters, but somehow every other nation on earth has figured out less violent ways of dealing with them. Yes, in many cases "the way" is to simply accept that wives will get beaten. Admitting this is no more an acceptance of police violence than admitting that not all nations are governed with perfect justice would be an acceptance of all of our damned wars. This is a "won't somebody please think of the children?!" level of argument.