She can’t do anything before the queen
If the queen decides she wants to stay up all night, Markle will have to do that same. She can’t go to sleep, when in the presence of the queen, until she does so. If the queen stops eating, Markle will also have to do the same.
Now that you know all of what her new role entails, do you believe you could make these type of sacrifices in order to be a duchess?