There may be some tznius problems with a man hitting a girl, so then she would have to hit him back for his breach of tznius and then it could go on forever until they are both dead.
Hitting back is not allowed, I’m afraid. The whole “מכין אותו” allowance is only to enforce the commandment before it’s breached. After the breach, she would be עובר on לא יוסיף by hitting him.