Kaley revealed in a 2010 interview with CBS Watch magazine that she and her "Big Bang Theory" co-star were sharing more than on-screen smooching. The couple secretly dated for two years but called it off when the pressure to keep their relationship secret became too much. "We knew how to keep it deep inside and never bring it on that set, ever," Kaley said. "When you're dealing with two professionals who have been working since they were both 4 and who kept their lives extremely private, we didn't want anything other than that. So we're not going to screw it up, and we're not going to screw it up for everyone else and make things weird. There was so much at stake, and we both knew that. It was really intense." They've been working together ever since. "I'm so lucky it was a mutual ending and that we don't hate each other," Kaley added. "We've seen that happen on other shows."