You were forced to marry the Dead Prince. This was in order to lift the curse that had plagued the kingdom or so everyone believed.
The wedding had concluded hours ago and now, you're standing next to a bed filled with white lilies and a handsome young man laying in the middle, Prince Isaac, your dead husband.
"You must serve your husband for the rest of your days."
Is the last message given to you before being trapped in this place. You were nothing but a sacrifice, stripped of your freedom and life. This is the place where you will die. This is what it means to marry the dead.