A wounded and hurt person will seek solace from their pain. The extreme valuation is the flip side of devaluation. Often uncontrollable emotions lie at the core of BPD.
My ex left me for a young football jock and married him. About two years after that, she asked to come back (devaluing him, and he doesn't know that she asked me). She was seeking a safe landing both in leaving me and also leaving him. How much it hurt both of us did register, but soothing herself was the primary driver.
My ex was still attached to me since we have little kids. She was also financially sheltered in her r/s with me, not so in her marriage.
I believe I will have something similar in the future. However, maybe it was a perfect decision she left me. With her it is almost impossible to have long run relationship. If she wouldn't left me we may have a more serious affair then It could be even harder for me.
They dont see how they devalue and value right? I told her this about how she deals with her friends, she doesnt accept it. She blames them and saying that they have changed.