You totally can! Just gather enough support from the Houses. You can still make an alliance and friendship with a love interest, without romancing the person, for the extra backing. You can also ally with and romance Mathys or Vesela and become queen while they be a secret lover lol. If you struggle to get all endings, there are guides on Blackcross&Taylor's own website, actually! https://blackcross-taylor.com/game-guides/