For better or worse: Private.
Once a woman and man agree to marry, what happens in that relationship should not be the business of society.
That might be a very practical approach.
If the guy beats her, don't come crying to society--you picked him.
Might make a woman think twice before marrying the guy with all the tatoos and the ring though his nose if society won't come bail her out later.
You are utterly heartless. I suspect you see women as either "good, wholesome, pure" or "sluts". No inbetween.
BTW, if the guy beats her ... isn't he liable at all? (smirk)
Age of Reason is definitely living in another age.