Conversation so far:
What happened in Gregory Hemingway's middle years?
In the course of his first four marriages, Gregory Hemingway had eight children.
Do we know why he had so many marriages?
Gregory's fourth marriage, to Ida Mae Galliher, ended in divorce in 1995 after three years, though they continued to live together and remarried in 1997.
Why did they divorce?
CANNOTANSWER.
Are there any other interesting aspects about this article?
Brave.
What is brave?
Maia Rodman, Hemingway's childhood tennis coach and a family friend who had fallen in love with him, dedicated her book The Life and Death of a Brave Bull to Gregory.
Did he have any other notable mentions?
He practiced medicine in the 1970s and 1980s, first in New York and then as a rural family doctor in Montana.
Where did he go to medical school?
CANNOTANSWER.
What other things did he do with his life?
authorities in Montana declined to renew Hemingway's medical license.

Question: Why did that happen?
Self-contained rewrite: Why did authorities in Montana declined to renew Hemingway's medical license?