After being with a BPD and educating myself I saw a lot of the same symptoms and patterns in a friend of mine. One day I asked him if he knew what BPD was and that I think he may have it. His next words were "funny you mentioned it, my therapist actually diagnosed me with it, I checked 10 out of 12 on his evaluation list". Same patterns, path of broken & destructive relationships, serial cheating, putting girls on pedestals, devaluing and discarding, future faking, fear of abandonment, ect.
He started seeing this new girl who his my buddy said is the first time hes never cheated. The day I met his gf our eyes locked, she smiled at me and later that night hit on me numerous times. After talking with her, learning about her past, I could see she also suffers from some mental disorder. They are so identical, I could see how they annoy each other to the max. He is starting to complain about her behavior, doesn't bring her out anymore, doesn't seem happy like he was just a month ago. Dont see it lasting that much longer, but relationships with broken people like themselves tend to last the longest.