I've seen discussion of this before, the answer was something along the lines of that the developer would first want to do Leandros, Koshiros and Ramos routes first, (aka the main ones) and that they have not made the final decision on whether or not they would even make option to have romanceable routes for other characters, since they would want to first finalize this game with these 3 different romanceable characters, and then they would make the decision on would they make other characters romanceable nor not. (CORRECT MY RESPONSE IF I REMEMBERED THIS WRONGLY)