I won't bother simply on the basis that I'm neither a psychologist, nor a social worker, and any quack college student could right now be putting out whatever. I don't even see this as grooming in this manga anyways, they're taking things VERY slow(as they should given the ages). Besides I view Romeo and Juliet clauses as good legal clause.
I think the most likely reason people these days just want to get angry at romantic youth usually because they're being riled up TO get angry at these things by social media. Much less likelier then that, they spent their high school(and even college years) single, and may even STILL be single to this day.
If you had a friend who maybe started their relationship with their long running wife of ten to twenty years going, had a nice family with kids, would you suddenly just unfriend them(and their wife) over this(or worse, try to ruin "THEIR" life) under these ridiculous online forms of justice? When you see a real ridiculous relationship like a 10 year old with a 25 year old or something, Yeah, It is bad.
This isn't that. And worse then that, its also just fiction so its truly irrelevent. How does it make you feel that I chose
Sadayo Kawakami when playing Persona 5? Comically I half chose her partially because I wanted the adult character over the kids, but took comedy in the age gap regardless. That's fiction, and there's nothing wrong with that.