I have AvPD (avoidant personality) and my ex has bpd. I only even noticed after she monkey branched. It wasn’t the cheating that got me, it was the cut off. 
It was obvious what she was doing but I thought we loved each other that we’d remain in each other’s lives as deep friends. 
I was hunting for answers as to how anyone could be so cold and cut you off so quick, and then discovered it was BPD and it just answered soooo many things for me.
We had our ups and downs but it was the longest and most deep relationship I’d ever been in. 
She was the only person I’d been with in my long line of casualships mentality that managed to lock me in a relationship, 
Honest to god I felt we were soulmates, and I can’t help but feel that me having AvPD was a blessing in disguise also, if I was fully all in, like a co dependant, I’d have gotten fucked even more.
I even remember a conversation where she was like, “if you was someone that gave me everything, i don’t think I’d be as interested in you.”
So while I move on and work to fix my own short comings, and disorder, I don’t think she even knows fully her disorder and I want to help. We’re not talking, while she goes and devours another relationship (poor guy doesn’t know what’s coming) but I know she will reach out. A relationship is off the cards, I can’t trust someone who has it in them to lie and discard me fully, but I will always love her and she has my sympathy for this disorder so I forgive her. She needs help.
I feel like the clingy Of bpd and the distance of avpd, it’s like a positive and negative that attract.