If you care about this person and want to support them, it's essential to be patient and understanding. At the same time, it's also essential to set your own boundaries and communicate your needs clearly. If you feel like you are being led on or kept in limbo, it's okay to express your feelings and ask for clarification about where the relationship stands.
Ultimately, navigating a relationship with someone who has BPD can be challenging, and it may be helpful for both of you to seek support from mental health professionals who specialize in this area. They can provide guidance on managing emotions, improving communication, and building healthier relationships.