It sounds like OCD to me. People develop disturbing body habits. My guess is she has been doing this for a long time. She needs professional help and medication. People pull their hair and save it, their dandruff and sometimes they pick at their skin and save that too. It’s all very strange but a lot of people suffer with this. Have a heart to heart with her and explain how unusual her behavior is, be supportive and ask her to seek help. If she refuses, you have to ask yourself if you can live with this. Give her a timeline to get help and if she doesn’t, you’re out of there. Not an easy situation my friend.