That's a very good decision you made, to still give it a sort of humor/romantic touch to the situation, while still keeping the 'end of the world' atmosphere for the characters! And yeah, a lot of VNs these days have dark narratives, which I still like to play, but... I don't want to spend an entire week mulling over characters (Like Echo, it broke my heart), heh
The part where I almost cried was... well.. around the time when Dia started to sort of... fight back against the infection? Telling herself to shut up and all. And also when the MC had no choice but to let go of her hand, and when he finally grasped what the hell happened when the initial shock wore off. I've seen many stories with mercy killings in them, but this one was one of the most hard hitting ones due to Dia doing it herself, and the MC very reluctantly accepting her decision-
And I'm glad to hear that! I do really think this novel has a lot of potential, hence my compliment! As a (online) writer myself, I can definitely understand the amount of joy you get when someone compliments your work!
You're honestly very talented, I eagerly await for the next build~!