Caroline Noel Franklin said that Kevin Knipple Wilkes had the softest lips when they first kissed in 1973.

It proved true again 49 years later.

“Every time I kiss this man it’s effervescent bubbles,” said Ms. Franklin, now 66.

In 1971, she was among 20 girls joining 60 boys in the first coed freshman high school class in 129 years at Trinity School in Manhattan. (The independent prep school, for kindergarten to grade 12, actually started out coed in 1709.)

“It changed the school’s sweaty, smelly nature,” said Mr. Wilkes, also 66, who entered Trinity in first grade.

Ms. Franklin went from “great crush to great crush” their freshman year, dating four different boys. Mr. Wilkes, a bit shy, waited on the sidelines.

“She was the ‘It’ girl,” he said. “I was just the awkward guy.”

By February 1973, sophomore year, he drummed up enough courage to call her on a rotary phone to ask her on what he considered the ultimate date — a Harlem Globetrotters game at Madison Square Garden on Presidents’ Day.

“I was extremely happy,” said Ms. Franklin, who knew nothing about basketball, but knew for certain that she had “developed a huge crush on this handsome, tall, broad-shouldered boy with southern manners and a slow, sexy drawl.”

Mr. Wilkes, whose family is from Georgia, took the train in from Westfield, N.J., where his family had moved from Riverside Drive in Manhattan, to pick her up at her parents’ apartment on Park Avenue, and then they took a taxi to the Garden.

They both stuck out at the game — he in a preppy crew neck sweater with an Oxford cloth shirt and she in a very ’70s plaid and corduroy empire-waist dress with a Johnny collar.

“We were overdressed to the nines,” she said.

After a few more dates he finally kissed her by the elevator that opened into her parents’ duplex penthouse.

“He put his arm around my waist,” she recalled writing in her marble-covered notebook diary, “and after the softest kiss, he gave a sweet, little sigh.”

They left notes for each other at their lockers, and went to many plays, often with her parents.

On Christmas Eve 1973, a day before her birthday, he dropped off five dozen red American Beauty long-stem roses with her doorman. Mr. Wilkes recalled going to the flower district at 5 a.m. with his mother, then an interior designer, and embracing “her exuberance.”

In May 1974, he broke up with her. They had been quarreling over intimacy, they said: Mr. Wilkes wanted more and Ms. Franklin was not comfortable with that.

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On her tearful journey home that day on the 96th Street crosstown bus, a man riding with his wife approached: “‘You see the woman sitting there,” she recalled him saying. “‘She broke my heart. He’s going to come to his senses like she did.’”

They did get back together soon, but only to break up again that December.

“She went north to Harvard and I went south to Princeton,” Mr. Wilkes said. After that, they usually only saw each other at a high school reunion every five years.

Mr. Wilkes graduated with a bachelor’s degree in architecture, and has a master’s degree in architecture from Yale. He is now an architect, and the founder and the managing partner of Princeton Design Guild, a construction and design firm, in Belle Mead, N.J.

Ms. Franklin graduated magna cum laude with a bachelor’s degree in English and American literature and language. She now teaches English and history at the Buckley School, a private day school for boys in Manhattan.

Ms. Franklin’s previous marriage ended in divorce, as did Mr. Wilkes’s. She has two sons.

In November 2021, over a year and a half into Covid, Ms. Franklin wondered what Mr. Wilkes was doing, and soon emailed him.

After emails flew back and forth, in February 2022 they went to Storico, a now-closed Italian restaurant at the New-York Historical Society, and then walked, arms linked, through Central Park.

“It was so clear we were in love again,” she said.

Later, at her apartment, she recalled how he very gently put his arm around her waist, and asked, “Do you want to try again?” She did, and they kissed. “It was just like kissing him at 15,” she said.

They saw each other every weekend, and went to many operas. That summer, he visited her in Watch Hill, R.I., with Sandie, his “65-pound slobbering English bulldog,” he said, where he met her sons and got reacquainted with her family.

On Christmas Day 2022, her birthday, they took a walk in Central Park with her sons, who suddenly disappeared. Mr. Wilkes then proposed along the reservoir, intentionally aligned with the Guggenheim Museum.

“On the axis with the center of the rotunda,” he said, with architectural precision, so that they could revisit the exact spot in the future.

On April 6, the Rev. Canon Steven Lee, an Episcopal priest, and the vicar at the Cathedral Church of St. John the Divine, led the ceremony there before 90 guests, who later celebrated at the Cosmopolitan Club.

“We danced, danced, danced,” she said.

Mr. Wilkes, who is now remodeling a house for them in the Sourland Mountains of Hopewell, N.J., said, “I tell those unrequited lovers in the world: Don’t give up hope.”