[Bond]

Personally, I don't ever plan on hitting either gender unless it's absolutely necessary (excluding past [friendly] fights with friends).

I think the answer to this question is: behave like a reasonable person, i.e. proper conduct depends on the situation. I'm not a fan of blanket statements here, but rather the situation must be judged in context. I'll give two extreme examples:

A girl punches a bodybuilder. If the bodybuilder were a reasonable person, he would detain the girl and not punch her.

A girl punches a young man into an inch of his life. If the young man were a reasonable person, he would be able to punch her to save his life.