Hi Reebz,
Welcome

,
I'm sorry that you are so confused about what is going on in your relationship right now. Unfortunately I can't tell you what is going on in your bf mind, but I can tell you this seems to be pretty common for someone with BPD. Often they will just push away those they are close to and sometimes it is for no reason that you can see.
The best thing I could say is to just give him some time. Try not to go chasing after him or repeatedly texting or calling. That will just push him further away. Give him a few days then maybe try to shoot him another text just saying, "Hey. I haven't heard from you in awhile. Just want you to know I'm here when you would like to talk."
Can you share what was going on in your relationship before he disappeared on you? Has anyone else seen or heard from him?