Britain's Prince William, Kate, Duchess of Cambridge, and Prince Harry
Britain's Prince William, Kate, Duchess of Cambridge, and Prince Harry take part in a relay race, during a training event to promote the charity Heads Together, at the Queen Elizabeth II Park in London, Britain, February 5, 2017. Reuters/Alastair Grant/Pool

Prince Harry has reportedly called on Prince William to be his best man at his wedding, but Kate Middleton will apparently not be Meghan Markle’s bridesmaid. There are good reasons for this, though.

When Harry and Meghan tie the knot in May, William will allegedly be Harry’s best man. It would be no surprise if he indeed took on the role because the brothers are close. William wouldn’t likely be called best man, though, as there is no such thing in a royal wedding, Marlene Koenig, a British and European royalty expert, told Town and Country magazine.

“The best man or best men are officially called supporters,” she said. “William will probably be Harry’s supporter.”

On the other hand, Harry could follow his older brother’s footsteps and break protocol. In his 2011 wedding to Kate, William assigned Harry to be his best man rather than call him his supporter.

Nevertheless, William is expected to take on a big role in his only brother’s wedding, regardless of what his part would be. The same cannot be said for his wife, who apparently isn’t likely to have a major role in what is sure would be a fairytale wedding.

Kate, who is pregnant with her third child, could even skip the event altogether as she is reported to be giving birth in April. But if the timing was right and she still could attend Harry’s wedding, she wouldn’t likely be at Meghan’s bridal party.

“The Duchess of Cambridge barely knows Meghan,” Koenig said. And even if she did, she still wouldn’t be a bridesmaid.

“For another, she is the future queen consort when William becomes king after his father, and would unlikely be an attending person to another royal bride,” she told Cosmopolitan. Kate is also already married, so if she would hold a role in the American actress’ big day, it would be as a matron of honour, which is reserved for a married woman.

But again, it’s unlikely she would be participating in that capacity. She was not even the matron of honour at her own sister’s wedding.

When Pippa Middleton wed James Matthews in May this year, Kate was not part of the bridal party. She instead helped with keeping the little children, including her kids Prince George and Princess Charlotte, in line. Kate reportedly did not want to upstage her sister and draw attention, which she would have surely done if she were the matron of honour.

Kate might be the only one in their family who wouldn’t have an active role. George and Charlotte are expected to be page boy and bridesmaid respectively at their uncle’s wedding, just as they were at their aunt Pippa’s wedding.