Tough questions! I know all healthy couples have disagreements sometimes, but they shouldn't say hurtful things to each other or get into physical battles. If they do say something hurtful, then I'd say it should be very rare, and then the person should apologize for saying it and work not to do it again. I don't think someone should keep doing the same wrong thing over and over. Apologies can be cheap and insincere.
Abusers always say they won't abuse the spouse again, but they will. They do. If a couple is under this kind of stress, then they need to get counseling immediately. If the husband won't go, then the wife should. And the wife shouldn't let it happen more than twice, at the most.
That's my take, off the top of my head, anyway.