Sometimes, you know he’s the one. Even when you don’t realize he’s the one.

Vaughan Bagley was licking her wounds over a breakup, describing her dream boyfriend. “I just want to find somebody like Ben,” she told her mother. “Somebody who can make me laugh.”

“Like Ben?” said her mom, confused. “The guy from Nantucket?”

Yep, Ben Maskell from Nantucket, one of the local kids from the Massachusetts island where Vaughan’s family owns a summer home called “Innisfree.” (Well, a mansion, really — but no one calls it that on Nantucket.)

The two met there 11 years ago, the summer when she was 17 and he was 21. She was a high school student, he a college student working summers as a caddie and in his dad’s landscaping business. The two hit it off — as friends.

“We kept in touch during the year,” Vaughan says. “But mostly we would just see each other in the summer.”

So, just buddies. Vaughan had boyfriends, Ben had girlfriends, and everybody hung out together on those lazy summer nights. She kept looking for “somebody like Ben.” He carried a flickering torch for Vaughan all those years but dismissed it.

“She was the most beautiful girl I had ever seen,” he says. “And I was really struck by her humility, her maturity even at that age. But she always had an air of unattainability.”

Unattainable? (As it turned out, no, but we’re getting ahead of the story.) It’s fair to say, however, that they grew up with very different lifestyles.

Before going off to Boston University, Ben lived year-round on Nantucket, where the population drops from 100,000 to 10,000 when the summer swells go back home. Vaughan grew up in A-list Washington — with a power couple as parents: Smith Bagley, an heir to the R.J. Reynolds Tobacco fortune, who died in 2010, and Elizabeth Frawley Bagley, a prominent Democratic fundraiser, appointed by President Bill Clinton as ambassador to Portugal. In addition to their Georgetown home, the Bagleys had the summer place on Nantucket, where Vaughan met Ben through a mutual friend. It was “like” at first sight — but a playful, platonic kind of like.

And then four summers later, when they were both unattached, something else blossomed. This time, love.

“It’s always hard to pinpoint what changes in a relationship,” Ben says. “But I remember there was a very distinct shift in how I felt. Leaving her was much harder. She dominated my thoughts in a way that hadn’t happened before.”

They had a long-distance romance for a year, while Vaughan finished college at Stanford and Ben worked in Boston as an aide in the Massachusetts legislature. Then they spent six years together in New York, where he got a master’s degree in social work and worked in the mayor’s office while she worked at nonprofit groups and on Hillary Clinton’s 2016 presidential campaign. It helps, of course, that they are both Democrats. (Next up: Oxford, England, where Vaughan plans to get an MBA and Ben a second master’s degree.)

“My grandmother always said, ‘You have to find somebody who shares your values, and ultimately humor should be one of those values,’ ” says Vaughan. “I never bantered the way I banter with Ben. We have a back and forth — both on the serious side and the funny side — that I’ve never had with anyone else.”

“We have a remarkable ability to communicate,” Ben says.

After all those years together as a couple, a proposal was not surprising — but the location was. Vaughan expected it to happen (where else?) on Nantucket. Instead, Ben popped the question in the garden of Sacré-Cœur Basilica in Paris.

Which brings us to Sept. 8: a cold, rainy Saturday when 180 guests — including Bill and Hillary Clinton, Sens. Ed Markey and Sheldon Whitehouse, former Virginia governor Terry McAuliffe, Chris and Kathleen Matthews, and Maureen Orth — gathered to watch the bride, 28, and groom, 32, exchange vows.

Technically, this was their second ceremony of the week. The first was an intimate Mass two days earlier for their families because the Catholic Church requires, well, a church. But Vaughan had always dreamed of getting married in her backyard on Nantucket, and so chairs were arranged overlooking the sea.

The American, Irish (a nod to the Frawley family heritage) and Nantucket flags began to flap. The rain started to mist, and the wind kicked up, bringing a chill to the late afternoon. “Mom has God knows how many pashminas, so she passed pashminas out to all the ladies,” Vaughan says. The bride wore a strapless Isabelle Armstrong ballgown; her mother and brother Conor walked her down the very windy aisle. “My veil went flying,” she says. “It was a very Irish wedding in that sense.”

The Rev. Peter Donohue, president of Villanova University, officiated, and Peter Yarrow (of Peter, Paul and Mary) performed — just as they had both done at Vaughan’s parents’ wedding in 1983. Something old, in the most sentimental sense of the term.

The party moved to the nearby yacht club, where the newlyweds shared their first dance to “Thinking Out Loud” by Ed Sheeran: “We found love right where we are.”

A good choice, all things considered, because there aren’t many love songs about Nantucket — but there are some sweet love stories.