Thank you so much for buying the game! As for the question: There's no way for the player to be married to multiple people due to the game's lore, but it's technically possible to be in a poly relationship if you marry president Camilla, since she already has other spouses. All other characters are monogamous and it is only possible to marry one character per playthrough. That being said, it is of course possible to romance multiple characters at the same time as long as you don't marry anyone (since marriage stops all romance with other characters), and the characters you romance won't interact with each other in any way.