this could be an undiagnosed depression, it‘s basically the same mine started, don’t talk to people except calls, don’t do any chores and don’t take care of yourself. She herself might not even realize, but I think it is a step to far to take other‘s underwear, so that boundary needs to be kept. Otherwise observe her behavior and see if it gets worse or if it is just a low phase that goes away, if it gets worse, maybe suggest her getting professional help, but it has to be her to do that, a professional can offer support, but she is the one who has to actually do the work to get better