My college girlfriend ended up diagnosed as bi-polar some time after we broke up - full on manic breakdown, conspiracy theory ranting, etc. She got help & some medication and is doing much better.
After her I dated someone I would say was uBPD. For some reason I picked up on the push/pull pattern and broke it off after a couple years and the 5th or 6th recycle after I realized the whole relationship was stuck in an endless loop.
After that, 4 years with someone who seemed wonderful at the time, left me and broke my heart - but in retrospect seems to have a great deal of narcissistic traits.
Now married to a uBPD waif for 10 years.
What's the common factor in all these relationships? ME

Also, all these women were the ones who initiated contact and the relationships with me, they are not women I active pursued or consciously chose to start dating.
Learning that I attract what I put out into the world and I need to learn to love and heal myself to stop my codependency, stop disregarding red flags and start being ok with being alone.