I met a girl back when I was 18 and really hit it off with her. She told me that her ex was scary because he punched his dashboard when he was pissed off. Her ex was a guy on the fringes of our social group, so I didn’t know him well.
A few days later we’re in bed and my roommate lets her ex in. He confronts us with a major “WTF?” Apparently she never bothered to tell him she was leaving him.
A few weeks later, she’s gone on to someone else and I’m best friends with the ex. We’re still on friendly terms decades later.