Although the premise is that one, they slowly start to get in love with the MC, especially from the oni girl (can't recall the name). On the other hand the yuki onna (the mother) was a slut from the start, and in her ending she also aknowledge it herself.
This alternate version drastically improves her personality.
It's exactly the premise that does not allow this nukige to be considered a romantic story of true love, even if they fall in love with MC if someone better than the MC appears with the condition of awakening, the girls could not resist him... that's why I think it's silly to be upset about the fact that they are easy girls. And as for the other... it was obvious that they would change her personality since a whore does not sell in the market XD.