In chapter 6, Daisy attends one of Gatsby's parties, and Tom insists on accompanying her because he is tired of Daisy "running around alone." Nick recalls that this party in particular had an oppressive air, pondering whether Tom's presence created this atmosphere.
As Tom and Daisy circulate, Gatsby points out the famous faces in the crowd. Tom claims to be unimpressed, noting that he doesn't "know a soul" there. Daisy, however, inflates the significance of the guests, desperately seeking to affirm the guests and the atmosphere. The guests are drunk, and even Nick notes that their drunken behavior has a "septic" effect on the gathering.
As they continue to observe the unrestrained social gathering, Nick realizes that the party is offensive to Daisy. This is quite a contrast to her typical social gatherings, which would be strictly organized and with tight social expectations of behavior. Though Gatsby's party is an elaborate display of his wealth, it does not replicate the social norms to which Daisy has been accustomed. The contrast between the socially exclusive East Egg, where she lives with Tom, and the "raw vigor" of West Egg, where Gatsby lives, appalls Daisy.
Gatsby is beginning to realize that Daisy has changed a great deal from the girl he fell in love with years earlier. Grasping, he insists to Nick that he somehow needs to "make her understand," because he feels the distance between their two worlds.