Kaley Cuoco & Johnny Galecki Dated: 'Big Bang' Costars Together Two YEARS

Kaley Cuoco secretly dated her 'Big Bang Theory' costar Johnny Galecki for two years, she revealed to CBS Watch Magazine .

The hit sitcom also featured their characters Penny and Leonard dating last year, but now both the real and fake relationship are over.

This is the first time I've ever talked about it, ever. It was a wonderful relationship but we never spoke a word about it and never went anywhere together. We were so protective of ourselves and the show and didn't want anything to ruin that. But that also made it sad, too. That's not the kind of relationship I want-I don't want to be hiding. We couldn't do anything. It wasn't as fun as we wanted it to be. 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... We knew how to keep it deep inside and never bring it on that set, ever.

We broke up before the holidays and worked that whole time. We dodged a huge bullet. Dodged a war. But 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..

I'm so lucky it was a mutual ending and that we don't hate each other. We've seen that happen on other shows.

Now the 24-year old says she won't date actors again, even though it ended on good terms and they still talk.

Galecki, 35, has yet to talk about the affair.