Cookie won’t like this! Empire costars Trai Byers and Grace Gealey are making sweet, sweet music off camera, sources confirm exclusively to Us Weekly. The costars have been dating since first meeting on the breakout FOX series.

“They started seeing each other during the shooting of the show. There was an instant attraction, people working on the show are aware about it,” an insider tells Us. “When they all hang out together they’ll cuddle and give a kiss, but it’s nothing obscene.”

Indeed, a second source tells Us that Byers, 31, and Gealey, 30, are trying to keep their budding romance on the down low. “They are having a great time together,” the insider says. (TMZ speculated of a romance after they were photographed at a wedding together.)

The couple’s real life relationship would be a no-no in the Lyon household. In the drama, Byers plays Andre Lyon, the son of music powerhouse Lucious Lyon (Terrence Howard) and firecracker Cookie Lyon (Taraji P. Henson). Gealey’s character Anika Calhoun is (spoiler!) Lucious’ now ex, and Cookie’s No. 1 enemy — or as she calls her, Boo Boo Kitty.

The lovebirds will have plenty of time to spend time together on and off set. Empire’s season 1 series finale drew in over 16.7 million viewers this month. In January, it was renewed for a second season after just two episodes.

Up next, they are planning a trip together before the cast heads back to work. “Trai and Grace are super serious,” a third source tells Us. “They started dating in the middle of the season and are completely in love.”