Responding to the news, Schnabel denied he's a cheat and said it was merely an "innocent situation" with a family friend.
But what about the other women Schnabel has been canoodling with in his years of being Klum's steady?
In a statement to PEOPLE, Schnabel said about pictures of him kissing a brunette mystery woman in London, "The claims that have been made are a misinterpretation of an entirely innocent situation. There is nothing more to this than I was simply saying goodnight to a family friend and we went on our separate ways."
However, is there really nothing to see here?
Mom of three Klum divorced rocker Seal in 2014 and started dating Schnabel the same year her divorce became final. She has stuck with Schnabel despite him being spotted with other gals.
As Radar has reported, cheating rumors flew about Schnabel after he was spotted on an apparent date with young actress Dakota Johnson.
During the 2015 night out, a source told Star, "They held hands on and off."
And also, New Yorker Schnabel was reportedly caught two-timing Klum with Russian Dasha Zhukova, 35, also an art dealer. According to OKmagazine.com eyewitnesses, he was "caressing, hugging and whispering into Dasha's ear" at the St. Moritz restaurant.
Still, Klum has told E! about Schnabel, "I'm very much in love."
The latest controversy erupted, as Radar reported, when he was photographed kissing the dark haired beauty Friday morning in London.
It raised major eyebrows as Klum, 44, was reportedly filming new episodes of America's Next Top Model in New York as Schnabel, 30, was in England with the other gal.
On Friday night, Klum was spotted in the rain in New York wearing a sleek leather dress and carrying an umbrella. She was smiling even as word was spreading about Schnabel kissing the other woman.
The supermodel was hard at work at Top Model while Schnabel was caught leaving the restaurant Chiltern Firehouse in London with the unknown female, around 3:30 am., as the Daily Mail reported.
And now, with Schnabel's hurried statement to deny cheating, observers wonder if Klum is in major denial about her relationship!
We pay for juicy info! Do you have a story for RadarOnline.com? Email us at firstname.lastname@example.org, or call us at (866) ON-RADAR (667-2327) any time, day or night.