Really, it's one thing to intellectually "know" she's not doing the right thing and quite another to change that behavior. Especially if she's ashamed of it.
I've known a number of adult riders that were inappropriately hard on their horses. I always thought that it was a reflection of how they treated themselves inside. Being a younger person at the time, I kept my opinions to myself and my horse on the other side of the arena ... but should I have a chance to help now, I sure would.
Best wishes that the situation has a good outcome.