The couple have been dating for two years and McAdams, 34 made sure to get Beckinsale, who is also the mother of Sheen's 13-year-old daughter Lily, on side once things got serious, reported Showbizspy.
"She gets along well with Lily and Kate, which was a deciding factor. Now they're definitely both in it for the long haul," a source said.
Meanwhile, "Twilight Saga: Breaking Dawn Part 2" actor is completely smitten by his Canadian love.
"He has known since the moment things turned romantic. She is smart and funny but also has a lovely romantic quality," the source added.
