On another occasion, when Leonard's mother was visiting, he and Penny came very close to having sex, but Leonard ruined the moment by suggesting that they were burying their lifelong issues with their parents by doing so, which offended Penny. In the second-season finale, when Leonard, Sheldon, Howard, and Raj were due to leave for a three-month scientific expedition to the North Pole, Penny privately expresses sadness, and wishes that he would not leave.