Hartnett reportedly met the 26-year-old British actress on the set of The Lovers in 2011, and they began dating in 2012, according to Page Six.
The 36-year-old actor recently admitted to having babies on the brain. While discussing working in Hollywood and money with Playboyrecently, he said, "If we could just help one another and express ourselves, we'd all be happy. But then I think, 'Oh shit, there are bills to be paid, and I'd have to get a car that's safe for my kid.' I don't have a kid yet, but that's the idea coming into my head these days."