Nick meets Tom and Daisy Buchanan and Jordan Baker at Tom and Daisy's house. As they are all talking, Tom gets a call, and Jordan tells Nick that "'Tom's got some woman in New York'" (Fitzgerald 18). Daisy also implies that she is unhappy in her marriage to Tom when she is complaining to Nick about being sophisticated and when she accuses Tom of hurting her.
Chapter 5 & 6
Nick meets Tom's mistress, Myrtle Wilson, and they all decide to go to Tom and Mrytle's apartment to talk with some friends. While there, Nick is told by Catherine, Myrtle's sister, that neither Myrtle nor Tom are happy in their own marriages, and it's Tom's "wife that's keeping them apart" because she is a "Catholic and [doesn't] believe in divorce", which isn't true (Fitzgerald 37). At the end of the chapter, Tom smacks Myrtle because she keeps shouting Daisy's name, and breaks her nose.
While attending one of Gatsby's parties with Jordan, Nick meets Gatsby for the first time. After this encounter, Gatsby suddenly asks Nick to go to go out with him to lunch and tells Nick "something about [his] life" so that Nick doesn't "get a wrong idea of [him] from all [the] stories" and rumors. After they have lunch, and Nick meets Mr. Wolfshiem, Gatsby's friend and business partner, he meets with Jordan who asks Nick for a favor in Gatsby's place, and explains a little of Gatsby and Daisy's history.
Chapter 8 & 9
Per Gatsby's request, Nick invites Daisy over to his house where Gatsby "coincidentally" happens to visit at the same time. Gatsby then invites Daisy over to his mansion and gives her a tour, showing off his various possessions. After this meeting, Gatsby happens to meet Tom one day and invites him and Daisy to one of his parties, after which Gatsby becomes depressed because he realizes that he's "far away from her" and "she doesn't understand" (Fitzgerald 118-9).
After Daisy and Tom invite Gatsby and Nick over, Tom decides to go to the city after he slowly becomes aware of Daisy and Gatsby's flirting. When they arrive in the city, they meet up in a hotel's parlor suite where Tom and Gatsby really begin to argue with Gatsby saying Daisy has "never loved anyone except [him]", and with Tom saying he would never give Daisy to a "common swindler who'd have to steal the ring he put on her finger", attacking Gatsby's job (Fitzgerald 139, 142). After this, Gatsby feels he must defend himself against the accusations and ends up revealing Tom's affair which causes Daisy to hit and kill Myrtle, in Gatsby's car, on her way back from the city.
In the morning after the fight, Gatsby tells Nick about his past with Daisy, reminiscing about how happy he was with her and hoping that they could still be together. However, later that day, George, Myrtle's husband, shoots and kills Gatsby after Tom reveals it was Gatsby's car that hit Myrtle. After his death, Nick holds a funeral for Gatsby, but no matter how long he waited with Gatsby's father, "nobody came", not even Daisy (Fitzegerald 186). Nick decides to return home to Chicago after ending his relaitonship with Jordan, and concludes that Tom and Daisy were just "careless people" who "smashed up things and creatures and then retreated", leaving others to clean up their mess (Fitzgerald 191).