No
hoshimota was right, the Player is given a chance to altar the letter in Question and asign any relationship he desires, though the game warns the Player about useing certain roles and slightly change dialogues if still done.
There is also a "3rd party" Patch that makes Roderick the werewolf in the hideout, which if left alive can also appear dureing the hide and seek game to fuck Arianna if left in the trunk alone.... also makeing Giron Frishas dad, etc.
At this point I doubt MC will become royality, simply by the fact that this would blow the scale of the game... Baron however is on the table with MC marrying Julia