Ebon Moss-Bachrach, who appeared with Bullock in 2006's The Lake House, describes the Oscar winner as "sweet" and "very professional" – with a generous side.
"I think on this day [she treated the cast to] Jamba Juice, if I remember correctly," Moss-Bachrach, 32, told PEOPLE at Thursday's IFC premiere of Breaking Upwards in Manhattan. "She bought a round for everybody."
His reaction when he heard the news of husband Jesse James's alleged infidelity? "Oh God, was I shocked … I just feel bad that her stuff gets aired like this," he says. "I just feel horrible for her."
Moss-Bachrach also says that the news was particularly difficult considering "that she had thanked him that way at the Oscars. It's pretty yucky."
Get a sneak peek of this week's issue – Sandra Bullock's divorce dilemma, Jolie-Pitt twin photos and more – which is on newsstands Friday