The couple met in 2014 at a Memorial Day party in Manhattan hosted by Ms. Zhou’s neighbor, the artist William Witenberg. Ms. Zhou was dabbling in the New York dating scene after moving from her hometown, Shrewsbury, Mass., in 2011 to pursue a career in finance. Dr. Wallack, who was divorced from his second wife, the Fox news anchor Jamie Colby, in 2011, was looking to revitalize his social life and cheer himself up when he accepted Mr. Witenberg’s invitation.
“I didn’t have anything to do, so I went to this party and there were a lot of people there and it helped my mood,” he said. “Then I saw Cynthia, and that helped my mood more.”
His good spirits didn’t prevent him from committing a minor social catastrophe. “He came up to me and spilled a drink on my dress,” Ms. Zhou recalled. “I don’t know whether it was intentional or not.”
Dr. Wallack, who has been chief of surgery at Metropolitan Hospital Center since 1996 and is also director of the surgical residency program there, has built a career on the steadiness of his hands. “I’m not going to divulge whether I spilled that drink on purpose,” he said.
What he will say is that he considers his act of clumsiness among the best moves of his life.
Dr. Wallack and Ms. Zhou, an only child who graduated from Dartmouth in 2011 with an art history degree, describe their courtship as standard-issue. After Dr. Wallack spilled his drink, “what was apparent to me was not only how beautiful she looked, but how beautifully she dealt with the conversation,” he said. “I knew right away she was older than her years.”
Ms. Zhou was equally impressed by Dr. Wallack. “He was handsome, he was a gentleman, and he made me feel very comfortable,” she said. He asked for her phone number and, like the old-fashioned suitor he said he is, waited a few days to call.
Their first date, at an Italian restaurant in Greenwich Village, came a week or two later. The conversation flowed, as it had on the phone when Mr. Wallack called to ask her out. Which, to Ms. Zhou, was itself an impressive gesture.
“Not a lot of guys call. Men my age will text you and want to meet at a dive bar. So I was really surprised when he called, and when I picked up he was really polite. He asked me how I was doing, how my day was. So it was just pleasant,” she said.
That pleasantness spilled into what turned out to be an almost, but not quite, perfect evening at Il Cantinori. Just after he ordered dinner, Dr. Wallack was called to the hospital on an emergency.
“That was a curveball,” he said. “Because I was really having a wonderful time. But it’s my job to take care of sick people, and at the time I had a patient who was close to passing away.” He smoothed it over with Ms. Zhou with reassurances. “I told her, ‘I’ll be calling you very soon, and I mean that.’ That night, after I had tucked everybody away in the hospital, I called her again.”
Ms. Zhou remembers that follow-up differently. A few days passed before he called for a second date, she said. But the wait fueled her anticipation. “I was really attracted to him on that first date, and I wanted to see where it would take me,” she said.
It took her to some spectacular places: They saw a series of Broadway shows including “Jersey Boys”; went to top-tier restaurants in the city; and, toward the end of 2014, to Puerto Rico for a five-day vacation.
“That was when I realized I could spend a lot of time with Marc,” Ms. Zhou said. “It was just the two of us for an extended period of time, and we didn’t get on each other’s nerves.” By then, Ms. Zhou considered their relationship exclusive. Dr. Wallack did not. But that was changing.
“One of the mornings I woke up in San Juan, she had made tea in the hotel room,” Dr. Wallack said. “And that made me feel so wonderful. I thought it was so elegant. After that trip I fell in love with her.”
A year later, a trip to England and Italy brought them closer still. Each recalls their vacation as “magical.” It was in Paris that Ms. Zhou said she started thinking she could marry Dr. Wallack. And Dr. Wallack began to distill what he loved about Ms. Zhou: Against the backdrop of beauty, youth and intelligence she presented, there was sophistication.
When they went to museums in France, it was evident how smart Ms. Zhou is, Dr. Wallack said. He found her appreciation of art infectious. “She didn’t try to tell me how she understands art,” he said. “It was just the way she acted, how at ease she was with it. The way she kind of translated that to me made me realize she was wise beyond her years.”
Three months later, Dr. Wallack was ready to propose. He went to the diamond district in Manhattan in search of a ring. And some advice.
“I didn’t really know what she liked,” he said. So he described their relationship, including the age difference, to salespeople and came away with a 2.6-carat solitaire — a nod to Ms. Zhou’s age at the time, 26.
On a March 24, 2016, trip to Albright College in Pennsylvania, where Dr. Wallack graduated and had been invited to speak, the couple took their time leaving campus. Dr. Wallack walked Ms. Zhou to the college science building, where he had spent long hours studying five decades before. It was dusk, and campus was quiet. He dropped to one knee and proposed. Ms. Zhou teared up and said yes.
And then her attention was diverted by professional goals. Ms. Zhou worked briefly for Credit Suisse after graduating from Dartmouth. In 2016, she enrolled in the M.B.A. program at New York University. Her studies there forced her to postpone wedding planning until this year, with many decisions, including the selection of her long-sleeved Monique Lhuillier gown with lace bodice and open back.
Ms. Zhou expects to graduate in 2018 and hopes to find work in mergers and acquisitions, the focus of this summer’s internship at Wolters Kluwer. In the meantime, she has little time off.
That is O.K. with her, though. “I came here to have a career on Wall Street, not to find a husband,” she said.
She acknowledges that the one she found anyway has caused raised eyebrows, and in some cases hackles, because he is so much older. When Ms. Zhou told her parents, Gary and Lily Zhou, of Shrewsbury, about the engagement, “it was a shock,” she said. “But they’ve come to terms with it. I’ve always been pretty independent.”
Mr. Zhou, the head of histotechnology at St. Elizabeth’s Medical Center in Boston, walked his daughter down the aisle in Westhampton and kissed her cheek before she and Dr. Wallack exchanged vows. Cynthia’s mother is a research associate at University of Massachusetts Medical School.
Dr. Wallack has not been immune to tension and doubt over his marriage to Ms. Zhou, either.
“The discussions haven’t always been pleasant,” he said of talks with some of the people closest to him.
Whispers about the May-December romance aside, both bride and groom have also felt the encouragement of trusted friends and colleagues.
Dr. Wallack said his residents and fellow surgeons are happy for him: “They know I’ve found someone I can love again after my second divorce, someone who’s going to keep me alive and engaged.”
Several hospital colleagues were at the beach wedding. After the couple read handwritten vows, Dr. Wallack stomped on a glass in keeping with Jewish tradition. Ms. Zhou grew up Presbyterian, but should the couple have children, they will be raised Jewish, she said.
At a reception in the hotel’s grand ballroom, Dr. Wallack’s friend and best man, Devon Reiff, a trial lawyer, toasted the couple with scant mention of age.
But just before the wedding he privately acknowledged the sea of doubters.
“The predominant reaction from everyone I know has been shock,” he said. “People just go: This is impossible, it’s ridiculous, it’s only going to last two or three years. I’m one of the only ones I know of who has been understanding. But it’s because I know Cynthia and they don’t. They’re both super-committed people and very serious.”
Ms. Zhou has found support in friends like Sonia Rao, a fellow art history student from Dartmouth who was her maid of honor.
“Cindy has always known what she’s wanted out of life and love,” Ms. Rao said during the reception. “She’s very sure of herself, and that’s been an inspiration to me. There’s always going to be stereotypes, but Cindy is strong. I’m excited for her.”