Posting this separately since it is not actually responding to
reidanota's question:
The game has an achievement (called "true love," maybe?) for romancing just one woman (or one threesome) and choosing her in the epilogue. It is possible to win the game without romancing anyone at all. You do have to max out your charisma, though. You earn charisma points by following the relationship paths of the five women in town.
For Nell and Primrose, the relationship path ends with a choice to have sex with them or just stay friends - either way, you get the point. For Callie, you have sex with her, then if she likes you enough, she invites you to upgrade the relationship and become her lover, and you either accept or decline (and get the point either way). With Evelyn, you get the point when you remove the inhibition that causes her to leave town if you tell her your feelings, but you don't have to ever tell her how you feel. With Samarra, I think you have to choose to have sex with her after defeating her in a duel to get the point.
If you read the adventure novel that awards a charisma point, then you can skip one of the five relationship paths and still max out your charisma. If you wanted, for some reason, to win the game while having as little sex as possible, you can skip Callie, say no to romance with everyone else in town, and win the game having had sex only with several fey, certain royalty, and Samarra.