What exactly are Dexter's "winter dreams"?
From the time he was a boy, Dexter longed for a life filled with wealth, beauty, and glamour. He was a romantic by nature, never able to accept the realities of his middle-class existence, always wanting more. His desires were heightened by the fact that he lived in a small community that provided services for the wealthy people who lived on Sherry Island, across the lake, and frequented the Sherry Island Golf Club. Thus Dexter grew up on the fringes of wealth, but never a part of it. Growing up in the proximity of a way of life so much more beautiful and exciting than his own created in him a longing that became a part of his nature:
[Dexter] wanted not association with glittering things and glittering people--he wanted the glittering things themselves. Often he reached out for the best without knowing why he wanted it--
Dexter falls in love with Judy Jones mostly because she embodies for him all of his romantic winter dreams. When he loses her, he survives with no appreciable change in his own nature. However, when he loses his romantic memory of her, Dexter also loses the ability to live within his own dreams:
The gates were closed, the sun was gone down, and there was no beauty but the gray beauty of steel that withstands all time.
With the loss of his dreams, Dexter is left to live with reality rather than romantic illusion.