Yeesh, I try to let stories go places I wouldn't got the sake of telling a story, such as this kind of age gap thing, but I simply cannot abide by this MC looking at a perfect woman who loves her and going "no! I don't want her, I want this person who's the same type but a child instead!" I can accept a protagonist who makes the wrong choice but that's a lot harder to stomach when the right choice presents itself on a silver platter and she deliberately throws it away. Considering what the primary differences between Mimai and Megumi are (age and vulnerability) it REALLY does not look good for this MC compared to if Megumi was the only thing going on in her life.
Kasane is written to be a self-aware pedo, there are so many instances where she addresses the glaringly huge problem (even if in a comedic tone). Ofc she would choose the child. It isn't a wrong choice, its a right choice for Kasane's character and is expected. The real question is whether or not the author would let them have a happy ending. (I really hope they don't and everyone gets therapy).
Most age gap stories include details to make it feel a bit less potentially gross, typically making the younger person the more aggressive one, making the older one really earnest and devoted, etc. This author instead boldly refuses to offer us anything to ease the discomfort, not even being open about the discomfort with framing like we're supposed to be disliking these choices. It's even stopped being a comedy and is just a straightforward drama about if our hero will get to fuck a kid or not.
The younger one is more aggressive here, but not for the sake of easing discomfort. So far Kasane has been the one to have these 'misdemeanors' being attracted to a minor and all. But for a change, Meguru is the one that initiated the kiss. WITHOUT CONSENT, while Kasane is incoherent and realllllyy drunk. We just get more and more uncomfortable by both characters, there's no longer a right side to be on, or a character to really root for.