As King Charles and Queen Camilla prepare to celebrate their 20th wedding anniversary on April 9, a royal insider says the monarch is still haunted by regrets from his first marriage.

According to the Daily Mail, a source close to the King revealed he “deeply regrets the pain and sadness caused” during his turbulent relationship with the late Princess Diana.

The insider added that “both Charles and Diana behaved badly in that first marriage and made decisions that none of us could ever condone,” but noted that hindsight offers new perspective.

“When you look back on it now, asking someone to sacrifice… happiness for the sake of their public persona seems really quite cruel.”

Despite public backlash following Diana’s death, Camilla stood firm. A friend of the Queen Consort shared, “I don’t think she was ever going to [step away from the spotlight]. She was committed to him.”

The couple’s 2005 marriage wasn’t without its hurdles. A former courtier recalled how the Church of England and the late Queen Elizabeth posed two significant obstacles. The Archbishop of Canterbury at the time was reportedly “unwilling to grant them permission to get married in a church.”

Instead, the couple settled for a civil ceremony at Windsor’s Guildhall — later described as “an elegant compromise.”

Now, two decades later, they’ll mark the milestone at a black-tie State Banquet in Italy, hosted by President Sergio Mattarella.