Maar pushed Picasso to paint the famous antifascist work Guernica, chronicled its creation, and even served as a model, having her hair glued to a early version of the painting. But maybe Picasso was so spectacular at depicting the horrors of senseless cruelty because he was often dishing it out himself. He once beat Maar until she fell unconscious, and he forced Maar to fight the mother of one of his children for his love. His years of abuse eventually produced a mental breakdown, with Maar undergoing experimental electroshock therapy. So you don't exactly need an art history degree to grasp the significance of Maar's nickname, the "Weeping Woman."
Still, Maar fared better than some of the others who were caught in Picasso's path. He once scarred a mistress by burning her face with a lighter. Another mistress hung herself. One estranged son was so dedicated to ending his own life that he succeeded even after an initial failed attempt of drinking bleach. Picasso himself declared that women are "either goddesses or doormats," meaning that had he been born later, he likely would have spent his days whining on Reddit about how the girls in his art class wouldn't go out with him.