Taxi (1978)

Season 4, episode 5

Zena asks Louie to drive her friend Emily, who has just been dumped and is drugged, drunk, and upset, back to her apartment. While there, Emily comes on to Louie and he ends up cheating on Zena. Louie soon brags of his conquest, but Elaine gets so angry that she is about to tell Zena everything. Louie decides to tell Zena himself though, who understandably dumps him. Louie then shows up at Emily's apartment, but Emily is clearly regretting her indiscretion with Louie and is getting back with her boyfriend anyway, so she kicks him out quickly. Louie, back at the garage, is in tears because he is so upset at the turn of events. Alex, feeling sorry for Louie, gives him some sage advice on how to get Zena back. All of a sudden, Louie turns off the tears and Alex sees that he's been had and gets furious with himself. As Louie goes to talk to Zena (and presumably gets back together with her), he assures Alex that the tears were real.