KELLIE PICKLER is so crazy about her “DWTS” partner Derek Hough pals say she’s forgetting she’s married!

The on-screen chemistry be­tween the toothy blonde twosome continues even after the cameras stop rolling, say sources.

“Kellie and Derek spend a lot of time together outside the dance studio,” a friend revealed. “They go to spas, head out shopping and grab dinner together in L.A.

“They’re like two peas in a pod, and Kellie admits she has a crush on him.”

MEANWHILE, her husband Kyle Jacobs, a 39-year-old songwriter who co-wrote Garth Brook’s No. 1 hit “More Than a Memory,” is back home in Nashville, Tenn.

“Friends have warned Kellie that she’s getting too close to Derek, but she says there’s nothing wrong with a flirty relationship just for fun,” disclosed the source.

“It’s like a fantasy to her. She says, ‘Oh, Kyle knows I’m coming home after all this is over.’”

But with the “Red High Heels” singer as the front-runner to take home “Danc­ing’s” mirror ball trophy, her hubby may have a long wait.

Judges gave Kellie, 26, and Derek the night’s highest score for their “Footloose” jive dance on “prom night” during the April 1 airing, and afterward Kellie cooed to Derek: “Thank you for being such a great date.”

But schmoozing with the stars is nothing new for Derek, who dated his Season 6 partner, “American Pie” hottie Shannon Elizabeth.

“Derek figured out long ago that having genuine chemistry with his partner is what both the viewers and judges want to see,” said the source.

Still, the 27-year-old pro has no intention of being a home-wrecker.

“I think Derek sees competing on ‘Dancing’ as a little romance that has a beginning, middle and end,” the friend explained. “He certainly doesn’t want to take up with a married lady.”