Top-socialite-turned-“Real Housewife” Tinsley Mortimer and coupon king Scott Kluth are back on.

“They got back together while Tinsley was filming. The distance was tough on them . . . He surprised her in New York several months ago and they picked up right where they left off,” an insider told us.

They’re renting a $30,000-a-month duplex penthouse at the Marmara Park Avenue hotel.

Mortimer’s even filmed a new commercial for Chicago-based Kluth’s CouponCabin with Carole Radziwill and Dorinda Medley.

Medley’s boyfriend, John Mahdessian, and Radziwill’s on-and-off beau, Adam Kenworthy, make cameos.