Dirty Danson!

Married Ted steps out with another gal.

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Ted Danson shared a late-night stroll in the Big Apple with a decades-younger stunner — while wife Mary Steenburgen was working thousands of miles away!

Our photographer caught the 71-year-old former “Cheers” stud deep in conversation with glamorous producer Keri Selig, 51, after the two shared dinner at a swanky hotel on Sept. 10.

“They exited the Four Seasons together around 10 p.m. and walked up Park Avenue,” spilled a spy-witness.

“They seemed to be discussing something important.”