On “Friends,” Joey’s girlfriend whom Chandler falls in love with in season 4 is Kathy.
Kathy is played by Paget Brewster and first appears in “The One with Joey’s New Girlfriend,” the fifth episode of season 4, which aired in 1997. Joey meets her and quickly begins dating her, while Chandler realizes that he has strong feelings for her. The situation becomes especially awkward because Kathy initially appears to be Joey’s new girlfriend, not an available romantic prospect for Chandler.
Chandler and Kathy eventually kiss, leading to a serious conflict between Chandler and Joey. Joey feels betrayed because Chandler crossed an important friendship boundary without speaking honestly with him first. The fallout continues in “The One with Chandler in the Box,” when Joey makes Chandler spend Thanksgiving inside a wooden box as punishment.
Kathy’s storyline is sometimes confused with Chandler’s later, more significant relationships with Monica Geller or Janice Litman. Kathy is a short-term character from season 4, but her plot is memorable because it tests the loyalty between Chandler and Joey and helps reveal how deeply Chandler can care about someone.