In “Winter Dreams” what ultimately destroys Dexter’s dreams?
The ultimate destruction of Dexter's dreams occurs in the final section of this brilliant story when he hears news of Judy Jones, the glittering golden girl that has formed a central part of his dreams, and her fate. Devlin, his colleague, tells him that she is now married, but her husband "treats her like the devil" and she is now only "all right" in terms of her physical appearance. Note how Dexter responds to being told about Judy's fate:
The dream was gone. Something had been taken from him. In a sort of panic he pushed the palms of his hands into his eyes and tried to bring up a picture of the waters lapping on Sherry Island and the moonlit veranda, and gingham on the golf links and the dry sun and the gold colour of her neck's soft down. And her moth damp to his kisses and her eyes plaintive with melancholy and her freshness like new fine lines in the morning. Why, these things were no longer in the world! They had existed and they existed no longer.
So, it is not the fact that Dexter does not get to marry his idol that ultimately destroys his dreams, but rather it is the way in which Dexter realises that the image he so cherished of Judy is irrevocably lost due to her looks that have faded. His memories of her now is all that he possesses.