My Partner Picks

My 19 year old girlfriend has picked her skin since her early teens. We've been together for over 18 months and I'd like to know if anyone here could give me advice on helping her stop. She told me really early on in the relationship which i thought was very brave of her. At first I thought that "telling her off" would be best but quickly realised this was making her more upset and guilty and was having an adverse effect. When I see her picking I normally tell her to stop and generally she just ignores me but sometimes does. Also, since her confession, she's started picking my defects as well, normally I do have some blackheads and so if i think there is justifcation to allow her to pick or squeeze, i let her. Is this a good idea? one thing I've tried, with success, is only allowing her to squeeze or pick my skin if she asks to me if she can pick specific blackheads first and stopping her completely if she doesn't, which now she does. I reasoned that picking my spots, that need sorting, in a controlled way was better than picking her skin unnecessarily. Is this logical? I really want to help her but don't know whether i'm doing more harm than good. and would really appreciate any advice.