you may not be considering that some deeper romantic commitment could come later on in the game, if i am not mistaken, Caro does want to build up the relationships very slowly, even though thane and nauxus are probably the most "boyfriended" ones for now. There is also the option of a poly or an open relationship to boyfriend more and/or bang around freely anyway, which would work for the obvious thing that players want to see every scene they can, so being limited by committing or not would be a bit of a chore for who wants to see everything (and potentially tons of variables for who and how many you boyfriended;). All the additional work would also have to be done considering that... some would never see it, since various npcs can die in various routes, and not everyone plays every route.
... Nauxus does have the best character and moments for me too tho~ even if my fav is Witer, slightly, but i'd go for an open poly anyway, so whatever~