I think the issue is that DPC changed his approach to Sage somewhere between Ep. 1-2. Not only did her character model get updated, but her personality too. She is introduced as a very self-centered person, willing to manipulate the MC to get what she wants, and showing a strong affinity for DIKs. That started to change as we see her interactions with others in her role as HOT president and as an intelligent, hard-working student - this wasn't a case of character growth, but rather simply different artistic direction from the creator. IMHO, DPC decided that relationships with the love interests would align better with CHICKS while DIKS would prefer lustful pursuits without commitment, thus we have two primary paths through the game with occasional crossovers.