Rachel McAdams and Ryan Gosling struggled to get along on the set of 2004’s “The Notebook.”As the rom-com celebrates its 20th anniversary on June 25, the director, 65, expressed his regret for ever discussing their dynamic in a new interview.“It caught me on a bad day, but if [McAdams and Gosling] are around, I apologize to you guys. I shouldn’t have spilled the beans,” he told Entertainment Weekly in a story published Tuesday. In a 2014 interview with VH1, the director disclosed: “Maybe I’m not supposed to tell this story, but they were really not getting along one day on set.