Allen and Harbour sparked dating rumours in October 2019 when the pair were spotted close together at a Knicks game in New York while Harbour was there to host "Saturday Night Live." But both Allen and Harbour revealed in later interviews that they started dating long before their courtside appearance in New York. In a 2021 interview with The New York Times, the "Stranger Things" actor explained that he met Allen while he was filming "Black Widow" in the spring of 2019. At the time, Harbour had a big beard and long hair for his acting role, but that didn't discourage Allen. "It's a true testament to my undeniable charisma when I say that my wife met me at 280 pounds with this beard and this hair. We went on a date at the Wolseley [restaurant] in London, and she really fell for me at my worst, physically and hair-wise," he said.
Allen touched on the first time they dated in a 2020 interview with The Sunday Times. She confirmed that their first date was at London's posh The Wolseley restaurant and that the pair met through Raya, a popular dating app among celebrities. Talking about their first date, the singer said, "I remember looking at him, and it reminded me of Leonardo DiCaprio in 'Titanic,' you know? When she's going to meet him under the clock. And, by the way, it was my first date ever. I had never been on a date! I was so anxious." She also admitted on "The Jonathon Ross Show" that she didn't realise he was star in "Stranger Things" as she hadn't watched the show. " I thought he was just like a sexy policeman from a reality TV Show," she said of her first impression.