David Harbour Spends Time with Wife Lily Allen's Daughter Marnie During NBA Game in N.Y.C.

Michael Simon/Shutterstock David Harbour with stepdaughter Marnie

David Harbour is loving life as a stepdad!

The Stranger Things star attended the New York Knicks basketball game against the San Antonio Spurs at Madison Square Garden in New York City on Wednesday evening, where he was joined by stepdaughter Marnie Rose, who turns 10 on Sunday.

Seen sitting courtside with Marnie — to whom he is a stepfather through his marriage to Lily Allen along with the singer's other daughter Ethel Mary, 11 — Harbour, 47, was captured with one arm wrapped closely around the preteen.

For the nighttime outing, Harbour wore a dark-colored polo shirt with black pants, while Marnie sported a black-and-white striped long-sleeve shirt and black pants, which she accessorized with a pair of Converse sneakers.

Other famous faces in attendance at the NBA game included Matt Damon and wife Luciana Barroso, Pom Klementieff, Jeremy O. Harris, Leslie Jones and Ziwe.

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Arturo Holmes/WireImage Lily Allen and David Harbour with her daughters

RELATED: David Harbour on How His Stranger Things Role Prepared Him for Fatherhood: It "Opened My Heart"

Speaking with PEOPLE back in 2020, Harbour explained that he is proudly involved in the lives of Allen's two daughters. "I'm in a relationship with three women who all have very different opinions of me at various times," the Hellboy star joked at the time.

But in all seriousness, "making that kind of a commitment, which I haven't for most of my life, was a huge thing for me," Harbour continued. "And it just makes you feel a little bit more like a man, to be honest. I just feel a little bit more like an adult."

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Being "thrust into this family role" not only changed his views on fatherhood, but made him feel "every cliché from every sitcom you've ever heard," the proud stepdad added.

"It's a cliché that we make fun of constantly in television and in books and I had always watched it with a grain of salt going, 'Eh, whatever, it's not the real deal.' And now I am in it," Harbour said. "That sort of hits it on the head."

RELATED VIDEO: David Harbour and Lily Allen Are Married! See Photos from Their Las Vegas Wedding

Allen, 37, and the Violent Night actor were first linked in January 2019.

They made their relationship social-media official later that year, when Harbour shared a photo of the pair enjoying a day at Walt Disney World in Florida.

The "Smile" singer and Harbour then tied the knot on Sept. 7, 2020, in a low-key ceremony in Las Vegas, which was officiated by an Elvis Presley impersonator and followed by a meal of In-N-Out burgers. The wedding came one day after the couple obtained a marriage license.

"I married a beautiful, incredible woman who I love," Harbour previously told PEOPLE. "I have never met someone who is so deeply kind as her. I've never felt so taken care of and cared for by another human being."

"She really is just a deeply kind individual and I love that about her," he added.