Complex sentence: Phoebe is the initial reason that Chandler quit smoking in "The One With the Thumb", after an argument between the group about his smoking he is leaving the apartment when she offers him $7,000 never to smoke again.
Split into simpler sentences: Phoebe is the initial reason that Chandler quit smoking in "The One With the Thumb", after an argument between the group about his smoking. He is leaving the apartment when she offers him $7,000 never to smoke again.