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It sounds like the person is self-mutilating and not trying to kill themselves. Many people are cutters; cutting themselves helps numb the emotional pain they are in by causing physical pain...some just like to see the cut & blood which distracts them. It can also be a form of self-punishment.
Cutting is usually a symptom of borderline personality disorder. Here is a link explaining that:
The best treatment for this is long term psychotherapy (a minimum of weekly for 2 years); sadly, 90% of people with borderline personality drop out of treatment before 2 years b/c they think it's not working & b/c they have trust & abandonment issues which make it especially harder as they feel they are getting closer to the therapist emotionally speaking. Some patients can even benefit from & handle 2X/week therapy.
In the meantime, here is a book for friends & families of cutters that is extremely helpful: Stop Walking on Eggshells: Taking Your Life Back When Someone You Care About Has Borderline Personality Disorder by Paul T. Mason and Randi Kreger
I hope this helps. Good luck & take care.
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