Ross and Rachel break up after Ross slept with "the Xerox girl" in Season 3 of Friends. The specific episode is titled "The One with Ross's Thing." In this episode, Ross is feeling insecure about his relationship with Rachel, and during a break from their relationship, he sleeps with Chloe, the woman who works with the Xerox machine at his office. This betrayal leads to the temporary end of Ross and Rachel's relationship, and they go through an on-again, off-again dynamic throughout the following seasons.