You should study what makes you defensive. The topic you avoid, the joke that irritates you, the question that feels insulting, the feedback you instantly reject. Defensiveness is usually the guard dog sitting in front of a weakness you have not trained yourself to face.
I can understand someone’s behaviour without accepting it lol.. I’m extremely good at psychoanalysis and understanding why people behave the way they do however that does not mean I need to accept said person
You can tell a lot about a person by what they do after hurting you.
Some apologize. Some reflect. Some change. And some will rewrite the entire story in their head just to avoid feeling guilty. Accountability is rare because protecting the ego is easier than becoming better.