Rachel McAdams gets along with boyfriend's ex

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.