His experience at being heir to the throne was a very bad one for him and so that's why he says that hes not fit for it, because of how much jobs and duties he had to take.
The burden is actually having to tell his friends the truth of his past and who he is.
Oh, that's Sonia, since she was the second born of the set of triplets.
His experience at being heir to the throne was a very bad one for him and so that's why he says that