Welcome to the board ,
I'm sorry to hear you struggling so much right now. It sounds like your relationship has been through a lot of ups and downs. Trying new things to work on the relationship will always be helpful, even if it's just helpful for you. Sadly though there is no way to determine if changing how you approach things will make everything work out because your partner still has free will to do whatever she is going to do.
Even though you can't control others, you can work on yourself. We have a lot of really great workshops on the right that can help you begin to work on how you approach conflict and communication with your pwBPD. Many people here have found that just beginning to use some of these tools affects the way their partner responds to them. Here's a link to one of our workshops on understanding your role in the relationship:
https://bpdfamily.com/message_board/index.php?topic=56206.msg913188#msg913188