According to a royal expert, Prince William and Kate Middleton represent the future of the monarchy, with their marriage characterized as a solid partnership.

Last month, the Prince and Princess of Wales celebrated their 12th wedding anniversary and played crucial roles in King Charles' coronation at Westminster Abbey on Saturday.

Nick Bullen, co-founder of True Royalty TV, discussed the couple's marriage and their significance as the younger face of the monarchy's future following the coronation. Bullen emphasized their partnership in both their marriage and their royal responsibilities as senior members of the royal family.

Bullen told Fox News Digital, "I think the secret of the Wales' marriage is that it is very much a partnership. If you look at other royal relationships that have worked, they've been partnerships."

He mentioned that Middleton actively participates in decision-making. The Princess of Wales is also said to be skilled at working with her occasionally temperamental husband.

Bullen explained, "I'm told very clearly that the Princess of Wales is very much part of the decision-making process in Kensington Palace. She knows how best to work with William. And William, as we know from the stories of his explosions with Prince Harry, can have a temper. And I think the Princess of Wales is very good at managing the Prince of Wales. It's a partnership, and he knows how good she is and what a useful tool she is for the royal family."

Bullen recalled the late Queen Elizabeth and Prince Philip's marriage, in which the latter supported the former.

He shared, "Prince Philip and the queen were a partnership. She might have been the woman on the stamps and the coins and the head of state, but they worked together. I knew Philip... I have been in the room [when] he said he knew his job was to work with her and support her, and that his service was to his monarch."

Bullen noted the shift in Prince William and Middleton's lives after the Queen's death, as the Prince of Wales went from being second in line to the throne to the heir, altering everything for the couple.

Bullen said, "He was always serious about his duty, and he always knew what his destiny was, but now it's there... I think you can see the seriousness in the Wales' in a way that wasn't there even a year ago."

He added, "We've recently been working with him in his role as president of the BAFTAs. And it was very interesting – his whole demeanor was, in some ways, more serious than I'd seen it before. The things that he wanted to be involved in were very serious causes that had a real purpose. He doesn't really want to talk about himself. The Princess of Wales doesn't want to talk about herself. They want to really focus on the causes and the things that are important to them, as opposed to about them."

During the coronation, the Duke of Cambridge performed several roles. He pledged loyalty and allegiance to the King and assisted in putting the robe on King Charles as the Stole Royal and Robe Royal. After the crowning, Prince William knelt before his father, placed his hand in his, and pledged his allegiance to the monarch. Then he kissed his father's cheek, to which the King replied, "Thank you, William."