The first time Erik William Ostberg saw Grey Alexandra O’Reilly she was sitting on a couch in her pajamas, feet curled under her, hair still wet from a recent shower. And, as might be expected of a woman who grew up in Ireland, she was sipping a cup of tea.

“I loved everything about what I saw, because I saw her true self,” Mr. Ostberg said. “I would call it love at first sight.”

It was August 2017, and he was in New York from Washington for a job interview. Afterward, he met a friend for a drink and was then invited back to his friend’s girlfriend’s apartment to watch a movie. Ms. O’Reilly was the girlfriend’s roommate.

“I thought he was really cute,” said Ms. O’Reilly, who learned that the Washington apartment she had recently moved from was only a few blocks from where he lived. “And when he left my apartment, he texted my friend, said he was interested in me.”

And so a few weeks later, when she was included in a group invited to spend the Labor Day weekend boating at Mr. Ostberg’s family home in Annapolis, Md., she didn’t hesitate.

“It was just a fun, relaxing time,” she said. “It just felt like he was meant to be there, and I was meant to be there with him.”

They shared their first kiss that Saturday, after a day out on the Ostbergs’ 30-foot center-console motorboat. A few days later, they saw each other again — also at a group event — when he returned to New York City to watch Rafael Nadal play in the U.S. Open.

“I just really liked him,” said Ms. O’Reilly, 28, who graduated from American University in Washington and is now studying remotely for a master’s degree in education from the University of Mississippi. “He brought me this sense of peace.”

Soon after, she took the train to Washington, where he still lived, for their first one-on-one visit.

“He told me he loved me a month later, and I don’t think he meant to,” she said.

The precipitating event, he said, was her selfless advice on a career decision he was facing: Take a job that he really wanted in Washington and commit to a long-distance relationship, or move to New York for another job plus the allure of proximity to a new romantic interest.

“And Grey told me, you have to do what you’re passionate about and take the job in D.C.,” said Mr. Ostberg, who is 30 and now a senior sales account associate at Hungry, a corporate catering and food delivery company in Arlington, Va. He graduated from Southern Methodist University.

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“That was the essential moment, being a good person and thinking about me,” he said. “It solidified that I was going to marry her.”

In September 2018, he found a job in New York and moved. When both their leases were expiring a year after that, they moved into an apartment together and soon acquired a mini goldendoodle puppy they named Lola.

Then came the pandemic.

The two stayed in New York until April, then went to his parents’s place in Annapolis. After three months there, they decided to take a road trip out to Montana, and ended up staying in Big Sky for 10 months.

“It was her first time seeing what the U.S. looked like,” said Mr. Ostberg, who proposed with his grandmother’s engagement ring in December 2020, while on a trip to New Orleans.

Soon after they returned from Montana, in April 2021, she obtained a head teacher position at the National Presbyterian School in Washington, and so by September, the two were once again — this time together — in the place where they had once lived as neighboring strangers.

The couple married Dec. 30 at the Circuit Court for Anne Arundel County, in Annapolis, where the groom grew up. Sharon Burke, a senior manager in the clerk’s office, officiated. And on an even larger scale, earlier that month, on Dec. 10, the Rev. Thomas F. Ryan presided over a religious ceremony at the Cathedral of Saints Peter and Paul in Ennis, Ireland, before about 240 guests.

It’s the small gestures, though, Mr. Ostberg said, that nourish their relationship.

“When I go on a trip, like for my bachelor party, she put in my dopp kit a ziplocked bag of Advil, Liquid I.V., some candy,” he said. “She just does every little thing. I will just come across little nuggets of love from her.”