Merriam,
You are posting on the bettering board where the goal is to stay with your pwBPD (person with BPD); however, what you have described sounds like you are more conflicted about separating / leaving him. If this is the case you might get a better response if you post over there.
With regards to the stages, Chains Candor made reference to, of a BPD relationship you can look at this article:
https://bpdfamily.com/content/how-borderline-relationship-evolves Even though I have not yet separated from my pwBPD, I too am tempted like you, and do fantasize about a day where I am not with them. If you don't have an individual therapist, you might want to get one to talk about this with them. Find one that specializes in BPD or high conflict relationships so you can understand the dynamics.
It sounds like you are very frustrated; however, it sounds like your parents are very supportive of you. Be mindful that your boyfriend will not change unless he wants to. You can persuade him a little bit; however, it is mostly on him to change. However, you can change what you do.
You may want to ask your parents to buy you the following books for you (or buy them so he isn't aware of them):
Stop Walking on Eggshells: Taking Your Life Back When Someone You Care About Has Borderline Personality Disorder by by Paul T. T. Mason MS & Randi Kreger (
3rd Edition) - it sounds like you may have already read this book, if it is an older edition, get the 3rd edition as it has an excellent assessment tool in it.
Stop Caretaking the Borderline Or Narcissist: How to End the Drama and Get on with Life by Margalis Fjelstad - this one has some excellent tools in managing a pwBPD
All of this can and is most likely emotionally draining for you. Be sure to do self-care whatever that might look like for you. For me it is therapy, exercise outdoors, hot showers/baths, getting lost in a good book/tv show-series/movie.
Read, ask questions, we are here for you.
Take care, with self-care.
SD