The Big Bang Theory Season 4 Episode 9 The Boyfriend Complexity

Sheldon's girlfriend, Amy, is introduced to Penny for the first time. Despite Penny feeling apprehensive about meeting Sheldon's girlfriend, the pair seem to hit it off and even bond over their mutual love for Penny's ex-boyfriend, Leonard. However, things quickly become complicated when Leonard accidentally reveals that he and Penny previously dated, causing Amy to become jealous and question the status of her own relationship with Sheldon. Meanwhile, Howard and Bernadette try to settle their ongoing argument about the cleanliness of their apartment. As tensions rise in both relationships, the group must navigate through the complexity of their romantic entanglements.