Hamilton, who will leave McLaren for Mercedes at the end of the season after signing a three-year deal, is believed to have cooled his relationship with the former Pussycat Doll due to his hectic work schedule.
After seeing photos of the American songstress cosying up to Brown in Los Angeles, Hamilton has decided to give their union another chance.
"Splitting was his decision," The Sun quotes a source as saying. "He's got a lot on his plate at the moment. And her commitments on X Factor and his career were clashing over the last few months.
"When he saw the pictures of her with Chris, he flew off the handle. He wasn't happy at all, even though they were not together any more."
Hamilton is believed to have flown to LA to speak to Scherzinger ahead of this weekend's Japanese Grand Prix.