Yes we do learn from our encounter with a person with BPD. We learn to distinguish between acceptable and unacceptable behaviours and what we feel comfortable with, and what not. I think it is because we were taken to the absolute extreme point. We thought we could deal with behaviours that were not entirely acceptable, we made excuses, we pretended to ourselves that we were not uncomfortable by it.
And then we were brought to our knees! We had to make a decision about what we are able and willing to put up with in our life, and what not.
I find that my

detector has kicked in now. Even in dealings with random people that I encounter, I notice the things that bother me and I distance myself from what I am not comfortable with. And I am re-evaluating some of my other friendships, too. I have tolerated some pretty weird behaviour over the years from some of my friends. Just the other day a friend of mine checked in with me to ask if my divorce was through yet, because some guy who had visited her house had seen a photo of me and she wants to know if she can send him my contact details! This is a friend who knows where I have been at, I have confided in her how difficult things have been for me and how torn I was about my marriage to a man with BPD. That I loved him, but that I could not live with him any longer and how painful it all is... . But I realise that she has always done and said inappropriate things that have sometimes hurt my feelings, but I just tolerated it and forgave her in my heart. I don't think I want that kind of friendship any more either... .