10x10 "The One Where Chandler Gets Caught"

Rachel and Phoebe see Chandler getting into a car with another woman. He dodges their questions by pretending to be at work but they follow him to the suburbs and find them entering a house. They believe he is cheating on Monica and tell Ross and Joey. The four of them tell Monica but Monica doesn't react the way they thought she would. It soon comes out they are looking to buy a house in the suburbs to raise their family (the woman having been their realtor). The group tries to convince them to stay in the city while reminiscing about the past few years. In the end Monica and Chandler get the house and tell everyone they are moving right after giving them gifts.