What you're watching is a man who optimized every variable in his life except his emotional infrastructure. He built a fortress of discipline around his body and his cognition, then handed the keys to one person. When you've eliminated most sources of chaos from your life, a single relationship becomes the primary vector for emotional volatility.
The more controlled the rest of your life, the harder a single attachment hits when it destabilizes.
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.
Good sleep should be considered its own PED class and I mean that in 100% seriousness
One of my favorite quotes on sleep “Sleep as much as your can without getting fired or divorced” wise wise words