Inside Jennifer Flavin’s divorce filing that ‘blindsided’ hubby Sylvester Stallone

Sylvester Stallone was said to be “blindsided” by wife Jennifer Flavin’s Aug. 19 divorce filing, as friends told Page Six how they looked “so happy” together weeks ago.

The “Rambo” star has been filming his upcoming Paramount Plus series “Tulsa King” in Oklahoma City, and friends said that Flavin — his wife of 25 years — has been on set constantly.

Sly was in Oklahoma when the papers were filed on Aug. 18 and sources said he was shocked to get the news.