Hi @Fabe,
Welcome to the Forums. My name is FloatingFeather and I am one of the peer support workers at SANE. You have found a safe space with many caring and supportive members with a wide range of lived experience.
I think it is really nice that you care so much about your friend that you are reaching out for advice from others. It speaks a lot about your character. It's a tricky situation if someone doesn't want to engage, talk, seek support etc. A close family member of mine has a serious mental health issue and at times (over the years) has wanted to be left alone and not engage. While I respected his decision because we all need time out sometimes, I would still try and keep the lines of communicate open just so he knew I was there if and when he needed someone. I would just send him a text every few days to check in and remind that I was around. I think at that stage in his journey he just needed his space (which I respected).
I know it's not always easy to want to reach out to someone if you feel like you are getting the brushoff but sometimes when people push others away it's because they are struggling the most. From my experience it is often the time they need the most support.
I wish you and your friend all the best.
FloatingFeather
I have attached a link to more information about borderline personality disorder - hopefully it might be of some help https://www.sane.org/spotlight-on/bpd