Maybe she was faced with a boat load of impossibilities?
Can you "just divorce" someone? No. You have to hire an attorney, figure out where you are going to live. Get all that in order, file, then wait until the divorce goes through. In that time, the WS may have to live with you if you can't afford a new place to live. Then you are subject to dealing with that person until the D is final, and who gets what is meted out.
If she was abused emotionally or verbally, that makes things harder. People get desperate. I'm not condoning it, I'm just saying, we are all human, and we can only take so much torture and feelings of helplessness before we snap. Some people have a higher tolerance than others....
I feel bad for her.