Hi Raemichelle,
Welcome aboard.
I am sorry that you are having difficulties with your relationship. It is really tough to take a step back in your relationship. I have been through a point in my relationship, where we had to take steps backwards. Surprisingly, taking steps backwards has helped improved my relationship with my person with BPD (pwBPD). It has given my bf and I the opportunity to work on ourselves, which has helped improved our relationship.
What types of things have hurt your trust in him?
Taking care of yourself is the one thing that you can do to help improve your relationship. Many times our relationships can be mentally exhausting and affect our self-esteem and confidence. Learning how to care for yourself first is really important.
Keep posting and sharing your story. You will find that there are many people who are going through similar situations.

Looking forward to reading your response.