My friend cuts. She's not clear on how often but I know she does and she wears hoodies 24/7. She goes to therapy and her mom knows but it's not helping. What can I do?

One of my other friends want to cut because of her on-off boyfriend and chaotic home life. Her 13 year old boyfriend isn't an excuse to cut. They date for two days at a time, and they don't even act like the other exists. I've never cut, but I do have depression that comes in waves. This might be tmi but... Help?