This is what I hate!

I watched this manga several years ago when I was younger, and I really enjoyed the story. However, it really pisses me off when we have inappropriate ages of characters. The plot at least in the anime cause I haven’t read this yet was so good, however, when you make one character, a legit child, and then the other character an adult for me it just takes away from the story. They really could’ve made the main character, a high schooler, and that would’ve been a lot more appropriate since the seme is 21. Like I could do a story where it’s 17 and 21 and it wouldn’t have been an issue, but 12 and 21 is wild! I literally came here because I wanted to actually confirm how old the ages are so I could justify reading this because the plot was actually so interesting. But I don’t think I can to be quite honest like why did the authors have to do this? It’s not like him being 12 versus him being 17 is gonna change the plot at all so it really just grinds my gears when the story becomes inappropriate when it didn’t need to be.