Hmmm. Good advice. My experience though has been with beyond difficult--it's been with a malignant narcissist and in the worst form of co-worker--a partner, a cousin, but while we were ostensibly partners someone had to be the boss and that was him. Kindness would not have worked. So after putting up with it for too many years I quit. Walked away with nothing but my life...at the time I had a very dependent personality and the shrink said get out because all too often those dynamics lead to murder or suicide.

Anyway, I could see a middle ground in what you describe. Understanding the other person for who they are understanding in myself why I would be so triggered and in that way avoiding the toxicity of resentment.