Most likely they are suffering from ptsd. My friend went into the military optimistic and spirited. While there, she was r*ped by her “boyfriend” and ridiculed by a significant number of coworkers. Leaving the military, her ptsd was so bad she couldn’t sleep with the light off. Every man she came across seemed to enforce her belief that men are terrible. It’s hard to find empathy for the thing that caused you so much pain in life