This question most directly pertains to Jay Gatsby. Gatsby's attempts to rekindle a love affair from his youth are central to his actions in the novel and, indeed, central to his character's ambitions.
Gatsby once loved Daisy briefly as a young man when he met her in Kentucky. After enlisted in the armed services and going off to fight in WWI, Gatsby loses Daisy to Tom, a man of great privilege and wealth.
Gatsby, at the time, has no wealth or status. He ultimately designs a plan to become wealthy, follow Daisy to the east coast, and win her love. Gatsby is out to prove something to the world and to himself. He is out to prove that he was always good enough for Daisy (or that, at least, his money makes him good...
(The entire section contains 394 words.)