Nick shares the social circle with Daisy and Tom, who he knows from his youth. He remembers Tom from his time at Yale, and Daisy is his cousin, who he visited after the war.
Detailed answer:
The characters of Francis Scott Fitzgeraldās The Great Gatsby have an intricate web of ties and social casts. The defining trait of such social circles is wealth. Rich people live in proximity to each other, throwing parties and living a decadent life. The poor, on the other hand, are excluded from the wealthy circles and inhabit in polluted, dark areas. Based on oneās notoriety in the community and their money, bonds with various individuals are broken and established. Nick, the narrator of the book, is one of the members of high society. It is thanks to his connections to the wealthy people in the East Egg. He settles in the West Egg, where the new-formed elites reside and are assimilated into their group.
Due to his connections, wealth, and manners, Nick finds himself accepted by the residents. In the West Egg, he also meets his old acquaintances, Daisy and Tom, who are married to each other. Daisy is Nickās cousin, who he remembers seeing some years ago. They met during his visit after World War I when the narrator spent a few days in their home. And Tom went to the same college as Nick, Yale, and shared a school club with him. The couple seems to remember Nick and be interested in his life. They have heard that he is getting engaged, reinforcing the notion of sharing a social circle.