Fitzgerald's book is basically an overview of his relationship and background of this love with Zelda.
Nick Carraway is a young man from Minnesota, educated at an Ivy League school (Yale), who moves to New York after the war. Also similar to Fitzgerald is Jay Gatsby, a sensitive young man who idolizes wealth and luxury and who falls in love with a beautiful young woman (Zelda) while stationed at a military camp in the South. (End of WWI)
The Jazz Age was a post-World War I movement in the 1920s when jazz music and dance became extremely popular. This allowed less strict policies on music, dress and dancing of that era.
The American Dream
Fitzgerald portrays the 1920s as an era of decayed social and moral values, evidenced in its overarching cynicism, greed, and empty pursuit of pleasure. The reckless jubilance that led to decadent parties and wild jazz music—epitomized in The Great Gatsby by the opulent parties that Gatsby throws every Saturday night—resulted ultimately in the corruption of the American dream. (Spark notes Overview)
the ideal that every US citizen should have an equal opportunity to achieve success and prosperity through hard work, determination, and initiative.