Why is Biff so angry at his father?

Biff Loman

The thirty-four year old son of Willy Loman, Biff was once a star high school athlete with a scholarship to UVA. But he never attended college nor graduated from high school, after refusing to attend summer school to make up a flunked math class. He did this primarily out of spite after finding out that his father was having an affair with a woman in Boston. Since then, Biff has been a continual failure, stealing at every job and even spending time in jail. Despite his failures and anger toward his father, Biff still has great concern for what his father thinks of him, and the conflict between the two characters drives the narrative of the play.