Season 6: Episode 146: The One With The Proposal Part II
Richard tells Monica he is still in love with her and wants to get married and have children. Monica wants a mature relationship that is going somewhere and is confused by Chandler's recent behavior. She decides to confront Chandler and get the truth about his feelings toward marriage. He continues to act like he hates marriage, but ends up taking his "plan" too far and upsetting Monica. She turns to Richard for consoling, but before things go too far, Monica realizes she needs time to think. Chandler believes he has lost his chance to marry her and goes to find her. When he returns home, Monica is waiting to propose to him and they finally get engaged. Rachel and Phoebe are concerned about being old maids. Rachel suggests that they both get married.