In The Great Gatsby, the mood is dark and pessimistic. The overall feeling in the novel is tragic. It is such a shame to live one's life chasing material gain only to come down to the end of life with nothing of value, nothing meaningful.
Jay Gatsby is a sad character. The reader has a sense of pity for Gatsby. He is a tragic character. The reader is left with a solemn, pessimistic view of those seeking material gain to try and find happiness.
After reading, the reader is left with a sense of hopelessness. What should be a romantic ideal turns into a devastating tragedy following the deaths of Gatsby and Myrtle. Also, Daisy contributes to the tension in the novel:
Daisy puts the constant tension between romantic ideal and cynical reality into words without even realizing it...
No doubt, the reader senses the tension and longs for some sort of reprieve with no relief in sight. The order of events proves to be lives filled with pretense. The reader can sense the facades of Jay and Daisy. Neither character is truly happy. The atmosphere is so pessimistic until the reader is grieved throughout the work. Truly the reader has to endure a range of emotions:
The mood is largely dark, pessimistic, and vapid as set by the purposelessness and carelessness of the wealthy, the ongoing string of meaningless parties, the ugliness of the Valley of Ashes, and the tragic deaths of Gatsby and Myrtle. Only Nick Carraway's honest and moral view of life breaks the sense of tragedy.