Welcome! There's some really smart people here who have been put through the ringer. My story pales in comparison to some here. I guess I should consider myself fortunate to only be dating for around 6 months before being discarded. Some others have relationships that last 20+ years. Imagine the turmoil that can put them through.
30 years down the road, the warning signs were there after 3 months. However, my partner made me feel loved like never before. Amazingly, after nearly 25 years of celibacy, I still feel a closeness with my pwBPD that can be unmatched. Unfortunately, 10 minutes late, I can be the "cruelest person" she knows!
About a month ago, my partner declared I have BPD. As a result, I read Stop Walking on Eggshells, saw a therapist specializing in the illness, and regularly visit this site. I am in a much better space than I was a month ago because of those three things.
Good luck and welcome!