Hi Lara99,
So, your girlfriend is treating you a bit like a stranger and you are feeling hurt? May I ask how you know she has BPD? Did she disclose this to you up front... .or?
Also, which of the symptoms of BPD does she exhibit? Are you currently in a relationship? Or hoping/trying to patch things up between you?
Would you say there is a push/pull dynamic in your relationship?
You can a learn a lot about BPD/BPD traits by reading the lessons to the right of the board here.

It is also really helpful to learn and share about this by reading/and offering support on others posts as well.
wishing you best, pearl.