Do you know why or have any speculation as to why Nyx didn't just skip the whole high school thing and toss everyone in college? Initially, I thought the fact he was still in high school was a little weird but I dismissed it as Nyx wanting create another layer of separation from the college crew (Erynn, Alexis, and Iris). Looking back, it seems to just create a headache having to deal with the ages in flashbacks.
I actually don't know the answer to that....but as you say, it creates a clear seperation from one set of girls to the other. As Eld stated earlier, it's why it will never be on Steam, Steam dislike girls in 'school' (because ultimately, despite saying everyone this age blah blah, there's actually about a 3 month window max where an 18yo would actually still be in 'school' and not already left for college). it's again, towing a line...one Steam dislikes. Uniforms? Steam, hate that even more lol.
Yes it creates issues...and has created an issue...it would have been easier to just not have the scene because now, there's like 18months difference between the MC and Erynn/Iris/Lexi etc etc....instead of what it should have been (so the 'flower' scene to Erynn makes even less sense now really when you think about it)....but hey *shrugs*..I just play it heh.