What is cluster B?
Zen606
Cluster B includes antisocial, borderline, histrionic, and narcissistic personality disorders.
(DSM5)
... .
any historical knowledge or theories available.
I don't recall coming across a historical take on it. There's quite a nice discussion about how BPD relates to modern society by Kreisman (2010,
link).
"Each culture probably needs its own scapegoats as expressions of society’s ills. Just as the hysterics of Freud’s day exemplified the sexual repression of that era, the borderline, whose identity is split into many pieces, represents the fracturing of stable units in our society." (Louis Sass in Kreisman 2010 op cit)
There's an interesting discussion about an individual's sense of stability and roles of social media in it. I liked how he connected the role of the family in explaining origins of nature v nuture type of stuff. I think that's consistent with what Skip's reminded everyone here:
... ."personality" is made up of many types ... .some of it is heritable and some do to the family style and some is do to the environment... .
I'd just recall that if you're in recovery, compassion can be to avoid jumping into the blame game if you discover factor X or factor Y playing a role in how a given ex was.
I hope you're finding peace.