I am a physical therapist and my H doesn't take my advice either when he "hurts" himself. I think the people closest to us do not value our "professional opinion." My BIL and other family members seek me out for advice but NEVER my H. I don't know why that is, it just is. Sorry I don't have better advice.
I just had a thought, it could be that she feels you are trying to control her by "advising" her. Just like with kids, sometimes they have to learn the hard way.
