Long before he became a billionaire, Mark Zuckerberg and Priscilla Chan started dating in 2003

Mark Zuckerberg drew “awws” from moms everywhere when he revealed he’d created a special invention for his wife, Priscilla Chan, in order to help her sleep better.

The Facebook co-founder, 34, said Saturday that Chan, also 34, inspired him to invent the Sleep Box, which emits a dim light between the hours of 6 and 7 a.m., so that she knows if it’s time to wake up and tend to their two daughters, Maxima “Max,” 3, and August, 1½, or whether she can continue sleeping.

“Being a mom is hard, and since we’ve had kids Priscilla has had a hard time sleeping through the night,” Zuckerberg explained. “She’ll wake up and check the time on her phone to see if the kids might wake up soon, but then knowing the time stresses her out and she can’t fall back asleep.”

He continued, “As an engineer, building a device to help my partner sleep better is one of the best ways I can think of to express my love and gratitude.”

The sweet gesture is just the latest step for the couple, whose beginnings stretch back to way before Zuckerberg was a billionaire.

Mark Zuckerberg/Facebook

August Zuckerberg, Priscilla Chan, Max Zuckerberg, Mark Zuckerberg

Priscilla Chan, Mark Zuckerberg.

Priscilla Chan, Mark Zuckerberg

The two started dating in 2003, after meeting in line for the bathroom at a party at Zuckerberg’s Harvard University fraternity when he was a sophomore and she was a freshman.

“He was this nerdy guy who was just a little bit out there,” Chan recalled to the New Yorker in 2010 of meeting her future spouse. “I remember he had these beer glasses that said ‘pound include beer dot H.’ It’s a tag for C++. It’s like college humor but with a nerdy, computer-science appeal.”

Chan, who grew up the daughter of immigrants in suburban Massachusetts, told the outlet in 2018 that she learned quickly that she and Zuckerberg came from very different worlds.

“Fifty percent of people go to college from the high school I went to. You could learn how to be a carpenter or a mechanic,” she said. “I was just like, ‘This person speaks a whole new language and lives in a framework that I’ve never seen before… Maybe there was some judgment on my part: ‘You don’t understand me because you went to [boarding school]. I had to realize early on that I was not going to change who Mark was.”

Zuckerberg and the pediatrician and philanthropist moved in together in September 2010, he wrote on Facebook at the time. In May 2012, they tied the knot in a surprise ceremony in their Palo Alto backyard.

A guest told PEOPLE that attendees thought the celebration was in honor of Chan’s medical school graduation — but it was actually their wedding.

“It was really cute,” the guest said. “Naturally people were surprised but happy.”

The ceremony took place just one day after Facebook went public.

“They share the same values and love and respect each other,” Zuckerberg’s sister Randi, 37, told PEOPLE at the time.

The billionaire gushed about Chan in 2016 while showing off his Time 100 Most Influential People cover, which he shared with his wife.

“Most days Priscilla works outside the spotlight in the hospital or the classroom. This is the first time she’s on the cover of a magazine,” he wrote in a Facebook post featuring a photo of the 2016 issue. “I’m looking forward to the world getting to know the strong, kind, compassionate person I love so much.”

Together, they launched the Chan Zuckerberg Initiative in 2015, which saw them pledge 99 percent of their wealth to causes including improving education and curing disease.

Facbeook.com/mark

Mark Zuckerberg, Max Zuckerberg, Priscilla Chan

“She just treats him like the guy she’s in love with, not the same Mark Zuckerberg everyone else fell in love with,” David Kirkpatrick, author of The Facebook Effect, told the New York Times in 2012.

The couple frequently offers glimpses of their family life on social media. In November, the husband and wife laughed alongside Max and August as they all wore coordinated looks.

“I’m thankful for time with family, and that all the girls went along with my plan for matching pajamas,” he wrote in the Facebook caption.

Zuckerberg also uses Facebook to share various milestones and celebrate holidays with his kids, like when Max started preschool in January 2018.

Mark Zuckerberg/Facebook

“First day of preschool,” he wrote. “They grow up so quickly.”