McAdams, 34, and Sheen, 44, took their romance public in October 2010 after meeting on the naturally romantic set of Woody Allen's film.
"Michael and I didn't get together while we were filming Midnight in Paris, which I feel strongly about not doing when I'm working. We became quite good friends, which I think is a great way to start," McAdams told The Sunday Telegraph's Stella magazine in January 2012. "I felt very blessed to have made a Woody Allen film in Paris together."
The Vow actress also shared that her most important relationship is good communication. "You need to trust each other and be able to talk to each other and be best friends."
During her relationship with the British actor, the paris remained steadfastly devoted to making it work. "Michael and I never spend more than three weeks apart — we rack up a lot of air miles — but you have to be quite adaptable in this business whether you are in a relationship or not," she told Stella.
The Canadian star's last serious relationship prior to Sheen was with her Notebook costar Ryan Gosling. The two began dating in 2005 and were briefly engaged, but called it off in 2007. Sheen had an eight-year relationship with actress Kate Beckinsale from 1995 until 2003; the two share daughter Lily, 14.