Looking to prevent a future breakup

If i'm on the wrong sdub, please tell me and I'll delete my post, but I was listening to some CAr Seat Headrest (famously a breakup artist) and I was curious as to why him, such a nice person, would be broken up with? And then i thought "I probaly shouldn't judge these things as I;ve never been in a relationship before" but I couldn't help my curiosity, and i was wondering if by posting here some people could give me some reasons why people break up, and I could work backwards to potentially prevent a future breakup. Please and thank you