A reader asked the following question (and I paraphrase a little):
Well, the quick answer is "she can be."
It's kind of the long answer, too.
The issue is at the investigation level, so this may be a better question for the cops. Essentially, in a domestic violence (DV) scenario they will do their best to figure out who the assailant is and charge the right person. I think you might be thinking either that the man always gets charged, or whoever calls the cops first gets the other person charged. Those two things are usually what we see, but only because that's what (in my experience) happens.
Sometimes, though, investigation shows that the person who called 911 is the assailant and, one hopes, the investigators can figure that out pretty quickly (by looking at injuries, talking to witnesses, etc.).
Perhaps not a very satisfying answer so let me know if I can elaborate further.