Kate Middleton's decision to refrain from public displays of affection with Prince William has raised speculation and curiosity among royal fans and experts. Despite the couple's strong and loving relationship, Middleton's choice to limit physical affection in public settings reflects their adherence to royal protocol and tradition. This decision may be influenced by the Queen's preference for maintaining a certain level of decorum and professionalism within the royal family. 

Additionally, Middleton's background as a commoner may have also played a role in her decision to adhere to the expectations of her royal role.

While the couple may display their affection in private, Middleton's actions suggest a respect for the boundaries and expectations set within the monarchy. Ultimately, the couple's decision to limit public displays of affection is seen as a reflection of their commitment to their royal duties and responsibilities.