‘The Big Bang Theory’ Co-Stars Secret Relationship

The Big Bang Theory‘s Kaley Cuoco stunned fans this past Wednesday with news that she and costar Johnny Galecki had a two-year relationship!

“It was such a huge part of my life and no one knew about it. It was a wonderful relationship but we never spoke a word about it and never went anywhere together,” Cuoco reveals in the upcoming issue of CBS Watch! Magazine.

Though Kaley and Johnny split six months before their on-screen characters Leonard and Penny did, they managed to keep the sparks going between characters until their break-up near the end of Big Bang Theory‘s last season.

Kaley admits that staying so low-key played a big factor in their choice to call it quits, saying, “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.”

Who knew all that on-screen chemistry was such a natural thing for the two former lovebirds? The Big Bang Theory is currently in its fourth season on CBS.