What does Nick mean when he says, "If that was true [that Gatsby might have realized that Daisy was not going to call] he must have felt that he had lost the old, warm world, paid a high price for living too long with a single dream"?

Now that Gatsby know that Daisy is not going to call, his dreams and fantasies is shattered.

Explanation:

The given quote is taken from the novella "The Great Gatsby" written by F. Scott Fitzgerald.

In the given quote, Nick is trying to convey to the readers about the dreams and fantasies of Gatsby.

Gatsby was a young man of thirty years of age. He fell in love with Daisy when he was serving as an officer in the military in World War I. His aim in life was to become rich for his love, Daisy. He purposed his life only to do things and buy things that would make Daisy happy, but his world of dreams were broken when he realized that Daisy is not going to come back to him.