Final answer:
The green light's significance fades for Gatsby as it symbolizes a dream that, once confronted with reality, cannot sustain the illusion or longing he had attached to it. For both Gatsby and Dexter in 'Winter Dreams,' the loss of their ideals signifies a profound emotional loss.
Step-by-step explanation:
The "colossal significance" of the green light at the end of Daisy's dock vanishes for Gatsby because it represents his dream and unattainable desire for a life with Daisy. Once he reunites with Daisy, the reality of the situation cannot match the idealized dream he constructed in his absence. The green light no longer symbolizes a distant dream but becomes just a mundane, physical object, stripping it of its power and Gatsby of his longing.
Similarly, for Dexter from Winter Dreams, the realization that the object of his affection, Judy, has lost her charm and beauty is a stark awakening from his romanticized visions. Both Gatsby and Dexter mourn the loss of their illusions and the emotional investment they placed in these dreams.