Although the couples in the royal family might love each other dearly, they are not supposed to show public displays of affection. Marrying a prince might seem like an actual fairytale, but you can't make a big show of it in public.
Holding Hands Is Even Frowned Upon
This rule mostly applies to the older generations of the family because the newer royals have become more relaxed about it. Like PDA, holding hands is technically against the rules, and you would rarely see the Queen and Philip holding hands in public.