As was mentioned in the previous post, Daisy is aware that her husband is having an affair. In Chapter 1, Tom receives a phone call from the woman he is having an affair with, and Daisy walks into the house, leaving Nick and Jordan alone on the porch. While Daisy is in the house, Jordan casually mentions to Nick that "everyone" is aware of Tom's affair. When Daisy returns to the porch with Tom, the phone rings again. Nick proceeds to describe the noticeable tension in the room between Daisy and Tom, who both realize that Tom's mistress is calling him again. Although Daisy finds Tom's infidelity unsettling, she passively accepts his actions. Daisy even comments that the best thing a girl can be in this world is a "beautiful little fool." Her outlook on life implies that she is aware of Tom's affair and is fed up with his behavior. Interestingly, Daisy has been aware of Tom's infidelity ever since the beginning of their marriage. In Chapter 4, Jordan tells Nick that Tom was caught cheating on Daisy with a chambermaid who worked at the Santa Barbara Hotel. In Chapter 6, Daisy even gives Tom her gold pencil to take down women's addresses at Gatsby's party. One could argue that Daisy's affair with Jay Gatsby is a response to Tom's continued infidelity.
Daisy does know that Tom is having an affair. Tom's dalliance is discussed early in the novel, in the first chapter, when Nick goes to have dinner with Tom and Daisy.
Jordan mentions Tom's affair when Tom takes a phone call during the dinner party, saying that it is Tom's mistress calling.
Jordan Baker, a female golfer and friend of Daisy, informs Nick of Tom’s affair with Myrtle Wilson in a noticeably nonchalant manner. Nick’s reaction is that Daisy should “rush out of the house” and escape this immoral situation.
Daisy, however, seems to resent the situation but also to accept it. The drama that the situation creates also creates a part for Daisy to play, a role, and she seems to enjoy the attention this role brings her.
Nick does not condone this state of affairs and it is something of a disappointment to his expectations. He had hoped to find a sophisticated social scene in the east, but instead finds a tawdry drama being played by his cousin Daisy and her husband Tom.