"She's a beautiful, amazing, compassionate human being who was thrown overnight into the middle of the media monster and has done an amazing job at staying true to herself and her family and friends," the friend says.
On Wednesday sources close to the couple verified that the pair, who dated for about a year, had parted paths.
"Yes, it's confirmed," one source says. "They've split."
Asked about the report, Clooney’s rep, Stan Rosenfield, would only say: "We do not comment on George's personal life."
Clooney, 47, and the onetime Fear Factor winner, 29, came out as a couple at the Venice and Deauville film festivals in September 2007. That same month, Larson suffered a broken foot when the two were injured in a motorcycle accident in Weehawken, N.J.
Larson was the first girlfriend to accompany Clooney to the Oscars, stoking rumors of an impending engagement that Clooney quickly shot down.
No word yet on who, if anyone, Clooney will be bringing to the premiere of his next project, the Coen brothers movie Burn After Reading, co-starring pal Brad Pitt, which is due out in September.
Reporting by MARK GRAY