Their relationship lasted for about three years, and they broke up in 2013.
Rachel Mc Adams was also in a relationship with Patrick Sambrook in 2013.
The news may come as a surprise to some fans who know the A-list star prefers to keep her private life private.
News can confirm the Hollywood star is pregnant and expecting her first child in 2018.
"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.
Since their split, Michael has been dating comedian Sarah Silverman.
Mc Adams was also in a relationship with Ben Jackson in 2009 but they broke-up after a year.
Soon after the breakup with Jackson, Mc Adams started dating Michael Sheen the same year.
PHOTOS: Biggest celeb breakups "They have know each other for a really long time — but have been spending more time together recently," a source close to Keagan told Us at the time.
Rachel met Michael Sheen in 2010, on the set of Woody Allen’s film Midnight in Paris.
Rachel Mc Adams is engaged to her screenwriter boyfriend, Jamie Linden. Ryan Gosling and Rachel Mc Adams Source: Pop Sugar Mc Adams then briefly dated Josh Lucas in 2009.