However, four months ahead of Harry's wedding to Meghan Markle in May, it seems the question still hasn't been popped.
Harry and Markle are set to Wednesday on May 19 at Windsor Castle, and it is speculated that William will be right by his brother's side, serving as best man. The Duke of Cambridge continued, "It could be a sensitive subject".
Last year, Markle also deleted her lifestyle blog "The Tig" after posting a personal message to her fans.
And with the Royal Family known for its age-old traditions, there is one wedding ritual Meghan will be following.
That's not the only drama that took place between the two sets of parents. "The couple of course want the day to be a special, celebratory moment for their friends and family".
There might be another reason as to why Harry's yet to ask William to step up - it could breech royal protocol. Here, the Life Bites podcast explores how to work through them. It is not clear whether Meghan Markle, who will become the Duchess of Sussex, will be included after the marriage.
The Collateral Beauty actress stopped by The Ellen DeGeneres Show on Thursday, January 11, and revealed that even though she starred as Queen Elizabeth II in the 2006 film The Queen, she will not be going to the nuptials.
It is likely, however, that Prince George and Prince Charlotte will nab roles in the ceremony.