Let me get this straight. People are outraged on Akito but they're all fine with Arisa x K...

I don't know where you got the definition of child grooming from, but Kureno x Arisa, Katsuya x Kyoko, and Shigure x Akito were not examples of child grooming. I agree that Shigure and Akito were toxic but Shigure never groomed her. Sure, he was manipulative and messing with her was the only way for her to see him as an equal, but he never was sexually active with her until she was an adult so they're not part of your minor x adult claim too. As for the other two couples, the men never groomed the girls. You may think that it was child grooming, but child grooming is building a connection with a child to take advantage of them for their sexual desires. Katsuya and Kureno were never lusting over the girls and it was blatantly obvious that it took time for them to realize they were romantically attracted to those girls only. I agree that those men were pedophiles, but they weren't child groomers. Maybe you wouldn't understand so you're free to think whatever you see fit.
I have parents who look like an example of child grooming (an adult who married a preteen), but they aren't. I'm not saying that relationships between a minor and an adult are okay, but there's a difference between grooming and a genuine relationship. I'm sure the reason why a lot of people are fine with those three couples is that those were never romanticized as minor x adult relationships and weren't examples of child grooming. Feel free to go back to reading the parts in the manga that featured those couples again.

Again with the grooming comments. Can you just go and actually take a course or something? I don't think other comments can even help atp