SAN DIEGO — It is the early 1980s. People have poufy hair and wear pleated pants and shapeless voluminous skirts. The someday-king (he hopes) of England, Prince Charles, is a man in possession of a fortune and in want of a wife.

He is consulting his mother, wise Queen Elizabeth, for advice on what to do about Lady Diana Spencer, the 19-year-old assistant kindergarten teacher he has been dating, if having a handful of chaste encounters constitutes dating.

Because this is a musical, the queen breaks into song. What is love, she wonders, considering the complicated example of her longtime marriage to the handsome but chilly Prince Philip, who has a wandering eye. Men may “take other friends,” but “it doesn’t mean devotion ends,” she warbles, before getting to the point: “Whatever love means.”

Charles, who unfortunately has a longtime girlfriend, Camilla Parker Bowles, who even more unfortunately has a husband, takes up the refrain, musing on his predicament: He is about to propose to someone he barely knows. He is perhaps the least qualified person in the kingdom to understand matters of the heart.

Longtime observers of the force of nature that was Diana, the princess of Wales — and there are many of us out here, despite the fact that she died more than 20 years ago — will notice that “whatever love means” is plucked from something Charles said after he and Diana announced their engagement, all the way back in 1981.

When the pair were asked whether they loved each another, Charles looked weirded out, as the thought had never occurred to him.

So that while Diana was murmuring, “Of course,” Charles was declaring, “Whatever in love means.”

It is this colossal mismatch of emotion and expectation that the makers of the new musical “Diana” have seized upon as the basis for this latest foray into the crowded field of Diana-divination. The production, still in rehearsals, is to begin previews Feb. 19 at La Jolla Playhouse before opening March 3; the planned run has already been extended through April 7.

There are many ways the Tony Award-winning creators of the show could have gone. In her relatively short and wholly vivid life, Diana was many things — naive victim, media-savvy manipulator, loving mother, fashion icon, lost soul, compassionate charity campaigner, femme fatale — take your pick. How you saw her depended on where you stood.

But at heart, said Christopher Ashley, director of “Diana,” she was a woman who dreamed of love — specifically the sort found in a romance novel or a fairy tale. And after landing a real-life prince, she discovered that princes — or at least Prince Charles — are not all they are cracked up to be.

Musical theater does love a princess — see “Anastasia” and “Frozen,” both on Broadway right now — but these are modern times, and marrying someone with a palace and a fancy title does not guarantee a happy ending.

“We were interested in Diana as a character who starts with one dream and actually gets it, and then has to find a new dream,” said Ashley, who is also the Playhouse’s artistic director.

The musical zips through her early life, settles into the royal romance and marriage, and — except for a quick epilogue tying up loose ends — concludes when that marriage breaks down and a liberated Diana breaks free to find her own voice and her own way forward.

“What I love is how she constantly changes her aspirations to advance herself,” said Joe DiPietro, who wrote the book. He is 57, around the same age as Diana would be, and supplemented his general understanding of her as a doomed mega-celebrity with extensive research from the exhaustive supply of books, articles and films available in the infinite Diana-sphere.

“I’m not a fan of musicals that try to tell about someone’s whole life,” he added. “What was interesting was the marriage. I wanted it to be very focused.”

Diana once said that there were “three people in my marriage,” meaning her, Charles and Camilla. The musical makes the trio a quartet by including Queen Elizabeth, who worked so hard, by all accounts, to keep the couple together, for the sake of kingdom and family. Other characters in the ensemble include Diana’s sometime lover James Hewitt, but the focus is on those four.

The royal-industrial complex is the gift that keeps on giving. Who among the journalists and biographers and filmmakers and television producers in Britain has not produced a work about the royals? But while most of the recent royal efforts have come courtesy of Brits like Peter Morgan (“The Queen,” “The Crown”) and Mike Bartlett (“King Charles III” on Broadway) this production is an all-American enterprise, reuniting the creative team behind “Memphis,” the left-field hit about the southern roots of rock ‘n’ roll that won the 2010 Tony for best musical.

“We’re two guys from Jersey writing about the royals,” said David Bryan, who wrote the music and collaborated with DiPietro on the lyrics. (You might know him from his day job, as the keyboardist for Bon Jovi.) “It would be like two Brits writing about the Kennedys,” he added. “In England, opinion is very divided, and so it helps that we’re removed from the controversy,” so we can see the story from an ocean-wide remove.

Their distance, too, has contributed to the production’s decision to not assign blame. It presents its characters as victims of circumstance, like protagonists of a Greek tragedy whose fates have been woven into the fabric of their lives.

Judy Kaye, a Tony winner for “Phantom of the Opera” and “Nice Work if You Can Get It,” plays Elizabeth. “When I was younger, in my mind I was taking sides,” she said of the end of the royal marriage.

“What we were being fed was that there was this young woman who was a total victim,” she said. “But nobody is a total victim.” She added: “I feel sorry for all of them.”

Charles’ tragedy, she said, is that tradition and expectation forced him to give up the love of his life, Camilla. (Of course, he ended up marrying her after Diana divorced him and then died in a fiery car accident during an ill-conceived excursion in Paris with her unsuitable lover, but that’s another story.)

During a recent day of rehearsals at the Playhouse, lines and lyrics and dance numbers and even whole songs were still being tweaked and reconsidered, as is often the case in the weeks before previews begin. A reporter and photographer were allowed to see only a few snippets.

One song, “This Is How Your People Dance,” laid bare the chasm of taste and temperament between Charles and Diana.

In the scene, Charles (Roe Hartrampf, with a Charles-ian side part in his hair) takes Diana (played by English actress Jeanna de Waal) to hear some music as a treat (supposedly). Not music she likes; music he likes — namely, Bach, performed by Russian cellist Mstislav Rostropovich.

He is transported. Diana does her best to keep up, first guessing that she’s hearing Mozart and then saying, in an effort to be charming, that she was “close.”

“Not really,” Charles says.

Her mind wanders. “The Russian plays on/Like an endless telethon/How I wish he were Elton John,” she sings, as she rises from her seat and (in her imagination, played out onstage) embarks on a wild rave with the ushers and other workers at the concert hall, dancing as a regular person rather than a royal.

It might seem weird to have a longtime American rock musician writing songs for a musical about the British royal family. But the characters’ musical tastes are vivid reflections of their characters. “We thought, what if we gave each character a musical voice?” said.

“Diana should be pop and rock. Her songs are emotional, and the chorus can get back, and there are more drums and keyboards. Kind of like my band.”

By way of illustration, he sang a few bars of Bon Jovi’s “Livin’ on a Prayer.”

Meanwhile, he continued, “Charles should be contemporary, but like a string quartet. The paparazzi are like punk guitars and the Clash. The queen should be classical with royal drums and regalness. And Camilla should be Lite FM, adult contemporary.”

In any production about real-life people, the challenge for the performers is to present an alternative that can drown out the reality in the audience’s heads. De Waal, for instance, bears a resemblance to but is no dead ringer for Diana.

She has studied videos, taking on the plumminess of Diana’s accent, the coquettishness of her walk, the tilt of her head, but it can only go so far.

“We’ve been very clear that we’re not making a documentary, and I’m not her,” she said. On the other hand, that “leaves a lot of freedom to explore who she was behind closed doors,” she added. “We’re conscious to show that there was a sort of mutual affection. She wasn’t delusional; she wasn’t mad; they did build a life together.”

Expect a major contribution from the costume designer, William Ivey Long, by all accounts an enthusiastic Diana obsessive who, by way of getting the job, tacked up hundreds of pictures of the princess in every outfit imaginable — her puffy-sleeved meringue of a wedding dress; the sexy sheath worn as a see-what-you’re-missing statement of post-separation independence — on the walls of his studio in Manhattan.

With early performances sold out and tickets sales brisk, expectations are high for “Diana,” which (as yet) has no current plans to transfer to New York. The Playhouse has become something of a crucible for Broadway, though not every show that originated here has transferred successfully.

"Memphis” played four years on Broadway, and “Come from Away,” which Ashley also directed, is still going strong there. But his most recent endeavor, the Jimmy Buffett jukebox show “Escape to Margaritaville,” ran for just four months last year.

In the end, Bryan said, the creators want to tell a human story of thwarted love — not just Diana’s, but also Charles’ and Camilla’s and, in a way, Elizabeth’s, too.

“This is such a human story,” he said. “Everyone thinks if they have castles and beautiful stuff, they’ll be happy. But stuff doesn’t make you happy. Our subtitle was one we didn’t use: ‘Trapped in the Kingdom.’ ”

This article originally appeared in The New York Times.