The Royal Family has a long list of rules and traditions that they've been following since coming into power. Some are quite understandable for monarchs, while others are just plain strange. But ever since the "rebellious" Princess Diana first said "I do" to Charles, many of those protocols have been broken. As we've seen most recently with Prince Harry and Meghan Markle'
https://www.trend-chaser.com/celebrity/oh-the-horror-times-when-the-royal-family-broke-protocol/