S01E24 The One Where Rachel Finds Out
Joey is taking part in a fertility study and he really likes his girlfriend Melanie but can't have sex during the study which lasts another week. The friends are having a barbecue for Rachel's birthday but without Ross because he has to go to China for the museum. Rachel unwraps the gift from Ross and its an antique pin exactly like the one her grandma used to have. Chandler lets it slip that Ross is in love with Rachel. Rachel goes to the airport to speak to Ross but he's already gone. Rachel decides to give her and Ross a chance and goes to pick him up at the airport.