The “other woman,” Myrtle Wilson, has broken a social taboo by calling Tom at home while Tom and Daisy are entertaining Nick and Jordan. When he takes the phone call, Daisy explains to Nick and Myrtle that he has “another woman” in New York City. Although upset over Tom’s affair, Daisy seems more perturbed by the fact that Myrtle has called Tom at an inappropriate time. This suggests that Daisy accepts Tom’s digressions to some extent. It seems money is more important to Daisy than a loving, faithful husband. However, Daisy “stringing along” Gatsby can be in reaction to Tom’s infidelity and her desire to hurt Tom for his affair. I wonder if Tom’s affair had included wealthy woman from their own social class if Daisy would have been less understanding about Tom’s philandering and more threatened.
Tom and Daisy’s marriage is one expected in a social class of wealth, and it appears to be loveless and unhappy. The affair just shows the morals of the wealthy class represented by Tom and Daisy who use people and throw them away as if they are trash.
In the opening chapter of The Great Gatsby, Nick is invited over to dinner at the home of Daisy and Tom.
During the meal, Tom receives a phone call and Daisy follows Tom into the house. While the two are inside, Jordan tells Nick that Tom "has a woman in New York."
Daisy gets upset, not only because Tom's girlfriend is calling him at home, but because she is calling at an awkward time. Tom's secret is not well kept at all, but this phone call almost seems to suggest that it is not even a secret anymore. The affair and the announcement of the affair (represented by the phone call) both upset Daisy.
It is no surprise that she then seems angry, offended and embarrassed.