It's difficult to predict any relationships longevity, circumstances and people change.
My BPD friend has had several long term relationships. She recycled with one of them, the rest ended on such a negative note there was either no desire from her to reconnect or the individual she was seeing took measures to ensure NC was possible.
Historically, every person she has ever dated has been eternally deamonized. I brought up her HS boyfriend (think 16 years ago) who she never more than kissed and she wished death upon him, to this day.
Same thing with this most recent EXBPD I dated, all her exes cheated, were abusive, mistreated her, etc. Then after I left she did the same to me, told people I was stalking her, said I cheated, I mistreated her, and even went a step further and had the new partner contact me to harass me. Of course after the break up I found out a lot about her that contradicted how she portrayed her exes. She cheated on one and left him for another, and when she started dating this new guy she was contacting me for sex, so I think that is actually one of the traits of the BPD, to demonize all past lovers and play the victim. When we dated she told me one of her exes was stalking her, the same one I later found out she cheated on and left for another guy, so again, same story all around. I also realized that all her exes are on her Facebook which I found creepy considering she trashes all of them.