Penny (Kaley Cuoco) and Leonard (Johnny Galecki) from "The Big Bang Theory" are one of the show's central couples, but fans had no idea Cuoco that Galecki dated in real life until the celeb couple had already broken up. They dated from 2007 to 2009, but keeping their romance under wraps put strain on the relationship.

"It was such a huge part of my life and no one knew about it," Cuoco told CBS Watch! magazine about her relationship with Galecki. "Everyone was always asking, and we deny-deny-denied. And I'm like, 'Why am I denying this person that I love?' It took a little bit of a toll on me and I think it did for him, too."

After getting out of a relationship, some people never want to speak or see their ex again, but this couldn't be more false for Galecki and Cuoco. Cuoco said they were never "weird" while working on "BBT" post-breakup, and Galecki told CBS Watch! in 2013, "We're dear friends [...] Kaley's not just an ex, she's part of my life."

Even though Cuoco and Galecki didn't end up together, they've thoroughly moved on. Cuoco has gotten married a few times, including to tennis pro Ryan Sweeting in 2013, while Galecki and his girlfriend Alaina Meyer welcomed a baby boy into the world in 2019 — Cuoco gets pictures from them all the time, of course.