Princess Diana shocked dance instructor and confidante Anne Allen with what she said after performing a spicy dance for then-husband King Charles at a 1985 charity event.

In the new book “Dancing With Diana: A Memoir,” Allen recounts the telling way the princess reacted once she wrapped a routine designed to surprise the future king, who seemed to be left less than impressed.

Allen, who grew close to Diana during hundreds of secret one-hour ballet lessons they shared from 1981 to 1989, hinted that the Princess of Wales was let down by Charles’ response, leading her to allude to unhappiness in her notoriously tumultuous marriage.

“She just wanted him to be thrilled,” Allan told People magazine in an interview released Thursday. “When you feel that somebody doesn’t love you, that has an effect on you. She kept thinking that there was love there and that there would be love there. And I’m sure there was.”

During a charity ball at the Royal Opera House in London in December 1985, Princess Diana teamed up with acclaimed British dancer Wayne Sleep for a piece of choreography set to the Billy Joel classic “Uptown Girl.”

Allen said the British royal was captivating as she strutted across the floor with Sleep for the jazz routine, especially during the climax of the dance.

In excerpts from “Dancing With Diana: A Memoir” published by People, Allen wrote that Diana’s “favorite moment” was when she provocatively placed her hands on Sleep’s head, “pushing him down into a kneeling position, then kicking one of her legs high over his head.”

“The audience loved the storytelling of the move,” the dancer recalls in the book.

While many in the audience were dazzled by the English icon’s moves, Allen remembered King Charles having a curt response to the performance, leaving the princess deflated.

Supposedly, all Charles had to offer was a short, “Well done, darling” before turning to talk to someone else.

“I sensed disapproval from him and my heart took a thud,” Allen writes in her memoir.

The princess’ own reaction was all the more shocking to her friend, who recalled Diana turning to both her and Sleep and telling them, “Beats the wedding!”

“Wayne and I were astounded,” Allen reveals in her book.

While Diana and Charles’ 1981 wedding was celebrated around the world, the couple’s marriage was said to be doomed from the start.

Throughout their 15-year union, the King reportedly carried on an affair with his former girlfriend, Camilla Parker Bowles, who now sits as queen consort.

As Princess Diana famously revealed in a 1995 interview with the BBC, “There were three of us in this marriage, so it was a bit crowded.”

After years of enduring an unhappy marriage, Diana and Charles separated in 1992 and finalized their divorce in 1996.

The princess tragically died in a car crash in Paris in August 1997, at just 36 years old.