The Oscar nominee, 28, gushed about being married to screenwriter and producer Tom Ackerley in PORTER magazine's Winter Escape issue in which she revealed the union made her "want to be better."
"Being married is actually the most fun ever," the star said. "Life got way more fun somehow. I have a responsibility being someone's wife, I want to be better."
While the pair have been married for close to two years, the Mary Queen of Scots actress said she doesn't like to spend too much time apart from Ackerley.
"Even if we both have to fly to a country in between where we both are for one night, we'll do it and then fly back to work the next day," she shared. "And we speak all day every day on the phone."
Robbie met Ackerley in 2013 on the set of the World War II drama Suite Francaise.
In May 2016, the actress told Vogue Ackerley was "the best-looking guy in London," and gushed about how she fell for him.
"I was the ultimate single gal," she explained. "The idea of relationships made me want to vomit. And then this crept up on me."
"We were friends for so long. I was always in love with him, but I thought, 'Oh, he would never love me back. Don't make it weird, Margot. Don't be stupid and tell him that you like him,'" she continued. "And then it happened, and I was like, 'Of course we're together. This makes so much sense, the way nothing has ever made sense before."
Robbie was given away by her mother and her three siblings were in attendance.
The actress is currently starring in Mary Queen of Scots, which is out Dec. 7. She is also portraying Sharon Tate in Quentin Tarantino's upcoming Once Upon a Time in Hollywood, and in the untitled Roger Ailes film.
To see the full interview, buy the latest issue of PORTER, on sale globally on Friday, Dec. 7, which is also available as a Digital Edition.