It seems to me after his affair became public..He became unbalanced. In spite of he and his wife’s problems, she seemed to keep him in some kind of check.
When he lost Robyn he became undone.
my opinion anyway.
For the middle part of his career, I think he was fighting desperately to keep his sanity. His three signature movies, Braveheart, the Patriot, and We Were Soldiers, were about a man who desired a safe family life, but ended up in the middle of chaotic battle. In the Patriot, in particular, his character had engaged in heinous acts during the indian wars, and was fighting that part of himself in his early refusals to take part in the rebellion.
During the time he was making these movies, he built his own church and attended masses in Latin. After the Passion of the Christ, he seemed to come unhinged again.
I think those three movies were somewhat autobiographical, in that his characters, while professing to want the safe family life, actually seemed far more alive when engaging in wild acts of violence. I know whenever I watched them, during the early setup, I was going, "Yeah, yeah, got the family. Go kill somebody, Mel." In his real life, the desire to become crazy was internal, rather than forced on him by Longshanks or the British army.