Your word ‘Pain’ jogged my memory.
The root of anger is fear. There was a book that I read a long time ago, can’t recall the author but it was about career criminals and/or first time offenders who resort to violence (anger) against people, places and things. Humans fear not being heard, respected, loved, understood, included, validated, etc. Primal.
The premise was that whether we have spats or major disagreements, fear is underlying. Even the famous ‘pick up your dirty socks’, for some people it can make them feel disrespected and not appreciated, resulting in harbored anger. ‘It’s so simple, why can’t you just do it for me???’
The author wasn’t implying that people murder their partners over socks but rather that fear can also be in the smallest of details.
What possessed this guy to choose murder instead of the healthy way to work through anger??? Radical thinking, radical actions.