First off, does she actually want to stop? If she does, not many therapists will specifically specialize in dermatillomania but lots of people have had success with CBT therapy. If it isn't actively upsetting her, I would suggest backing off. Dealing with dermatillomania is not easy, it's considered an OCD adjacent disorder and a lot of the techniques are similar, aka learning to sitting in massive discomfort and anxiety and not doing your soothing mechanism. If she doesn't 100% want to do it, its not going to work. It also seems like maybe you could also use some therapy yourself, because it seems like you have anxious attachment and that's driving all of this. You talk about this like is some project. She reports, your best assessment, etc etc. Nobody wants to feel like a research subject in their relationship, or that their issues are under intense scrutiny by their partner. You can't fix her, but you can support her. Heading over to r/compulsiveskinpicking could help you get a baseline understanding.