Face it. Men are suckers for a crying woman.
As soon as the tears start flowing, a man’s entire set of defenses falls in the face of her sorrow. (Or her contrived sorrow, depending on how good she is at crying on cue.) He is suddenly at her mercy, ready to do whatever it takes to prevent such a scene from happening again.
Legend has it that monsters’ cold hearts could never be warmed by the tears of the women they loved. The female creatures and goblins of the underworld came together one day to beg the monster king for a way to get through to their beastly spouses. The king relented, and taught them how to undeniably capture their mates’ attentions.
Thus, female monsters of all degrees and types learned how to cry blood. And they became the winners of all marital arguments from then on out.