If you read "A River Runs Through it" which is a biography of sorts, he has some lengthy narratives that are about his train of thought while he is on the river that are very Ni. He gets lost in his thought. He is very dutiful and responsible in contrast to his brother Paul, who is an ESTP, and he is addressing problems that could be understandably emotional, but he remains very rational through his analysis. One of the central themes of the story is the inability to help a loved one. Here is a quote about his reasoning, but it was integrated into that story as a quote by his father:
“You are too young to help anybody and I am too old.”…”Help,” he said “is giving part of yourself to somebody who comes to accept it willingly and needs it badly.”
“So it is, that we can seldom help anybody. Either we don’t know what part to give or maybe we don’t like to give any part of ourselves. Then, more often than not, the part that is needed is not wanted. And even more often, we do not have the part that is needed. It is like the auto-supply shop over town where they always say, ‘Sorry, we are just out of that.’”
The message that I received from the story is that we can’t understand anyone of our loved ones fully so we are unable to help them in the way that they need. The only method of assistance that can be offered is to love them completely and unconditionally, and hope that the love that is offered is an adequate form of support.
He also understands the complexity of the individual, and at the end, he makes the statement “you can love completely without complete understanding.”
I have more evidence, but I don't want to spoil the story.
He notes the woman's attempt to solve the problem too, and questions their F tendencies in trying to help. His mother is an ISFJ, and he states that her attempts to help "through choke cherry jelly" are superficial. He might sound like an F, but he is a T. There is another character that his wife's family is trying to help as well, and he questions their methods too.