Robert Ashton Conner had to adjust his expectations when he met the water polo star Margaret Ann Steffens on Dec. 3, 2016.

“I was expecting a massive person,” Mr. Conner said, when she arrived at the Old Pro, a bar in Palo Alto, Calif., for a birthday party arranged by a mutual friend. His cursory knowledge of water polo had left him with the impression that its players were tall, muscled-up blondes. Ms. Steffens, who is five-foot-eight and brunette, was not that.

But the poise and self-assurance that had led her to Olympic gold medals with the U.S. women’s water polo team in 2012 and again in 2016 was apparent. “Maggie has such a confidence to her,” Mr. Conner said. “She came into a party of guys celebrating a birthday and bought tequila shots for everyone.”

Driving home that night, he was determined to see her again, even if it meant arranging a first date from hundreds of miles away.

Ms. Steffens, 30, grew up in Danville, Calif., in a family of aquatic notables. Her father, Carlos Steffens, picked up water polo in his native Puerto Rico and later became an All-American at the University of California, Berkeley. Her sister Jessica Steffens, one of three older siblings, was among her teammates at the 2012 Summer Olympics. Ms. Steffens started playing at 8 and joined the USA Women’s Water Polo National Team at 15. “It’s definitely a family affair for me,” she said.

She was a year away from earning a bachelor’s degree in science, technology and society at Stanford when she was invited to the party at Old Pro. “I was 23 at the time because I had to take gap years for the Olympics,” she said. “So I wasn’t really wanting to go to frat parties. A bar was perfect.”

And so was the drink Mr. Conner bought her after she treated the crowd to tequila: a Cuba libre. “It’s the drink of Puerto Rico,” she said. “I was like, this guy knows me.” Even better, “he had a rhythm and confidence to him. I thought, he’s a very attractive man.”

Mr. Conner, 31, whose nickname is Bobby, is from Marin County, Calif. His family owns a winery, 689 Cellars, in the Napa Valley; he works in sales and production there. He knew little about water polo when he met Ms. Steffens. “I had never watched a game in my life,” he said. His sport was soccer. He played it at Saint Mary’s College of California, where he earned an M.B.A. in 2017 after graduating in 2015 with a bachelor’s degree in business administration. He was his team’s captain. He was living in San Francisco when he got his invitation to the party in Palo Alto.

The holidays complicated his plan to see Ms. Steffens again. His family, vacationing hundreds of miles south in Newport Beach, was waiting for him to join them. But “Maggie was the first person in my life I was immediately drawn to,” he said. “I had to see her more.” At the party, he secured her phone number. The following day, he asked her out via text. On Dec. 22, two weeks after meeting her, he drove six hours to pick her up in Danville.

Instant chemistry followed them into Havana, a Cuban restaurant in Walnut Creek, Calif., on their first date. “We immediately had this amazing connection where we could be our authentic selves around each other,” Ms. Steffens said. “We were both like, Wow, this is somebody we could marry. It kind of scared both of us.”

Mr. Conner was in love by the time they kissed good night. Within weeks, he was driving to Palo Alto from Marin County every Tuesday, Ms. Steffens’s only day off from practice. “Bobby’s a man of effort.”

In addition to her water polo career, Ms. Steffens is a businesswoman. Before she earned a master’s degree in management and engineering from Stanford in 2018, she helped found the youth athlete analytics company 6-8 Sports. Her international reputation as a professional player was already well-established. In 2017, she joined the pro team in Hungary, where Mr. Conner came to cheer her on. Then, in 2019, when she moved to Barcelona to play, he packed his life up and followed her there. “He was willing to move across the world for me,” she said. They lived together in Spain almost two years, then returned to California at the onset of Covid.

They had already bought the house they still live in, in Long Beach, in 2021 when Ms. Steffens, as captain, led her team to its third Olympic gold medal in Tokyo. The postponement of the 2020 games because of the pandemic had come as a blow after years of training. “It was difficult,” she said. “Bobby was my support system.”

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On July 8, 2022, during a sunset boat ride near their home in Long Beach, he surprised her with a diamond engagement ring that had belonged to his grandmother. Ms. Steffens, who hadn’t made a secret of her readiness to be engaged, was elated.

On Nov. 11, they married at the Caribe Hilton in San Juan, Puerto Rico. Ms. Steffens’s brother, Charles Thomas Steffens, was ordained by the Universal Life Church to officiate before 135 guests; most, including many of Ms. Steffens’s teammates, had flown in from California.

“My coach gave me a week off to celebrate my wedding,” said Ms. Steffens, who is now training for the 2024 Olympics. “We’re enjoying every minute.”