What is the main conflict in When Nietzsche Wept by Irvin D. Yalom?

On advice from his friends, Nietzsche travels to Vienna to see Dr. Breuer. He has been afflicted with migraines and feels desperate for help with them. Nietzsche is reluctant to put his trust in Dr. Breuer, but after Dr. Breuer saves Nietzsche from a brutal migraine attack in the middle of the night, their relationship improves.