you missed the point as to why uke thought seme didn't love him. seme went on about saying it's easier to not think about feelings - which he was struggling to figure out ever since before because he has already started falling in love with uke and worked his brain to understand it for him. uke thought that was seme just trying to get into his pants, which was incorrect, but because of seme's frustrations about his struggle to understand emotions plus seeing uke with a guy that just told him that he may want to steal uke then he snapped like a kid and it came across just like how uke thought seme felt.
it's subtleties like this that are usually hard to grasp for some people especially in non-lighthearted mangas like this. I believe he was also made as 17 to emphasize the "a kid so close to becoming an adult" which is the whole theme of the story: his age constantly being talked about in comparison to his face; his actions being impulsive and immature; him mentioning he wanted to grow up as a proper adult so he learned how to apologize. Then you see by the end how he transformed into an adult properly. that is its potential, and the message it wanted to tell came across just fine.
Bro why do i have to be not wanting them to be together like why couldnt the author make the model 20??? like its young but not ILLEGAL young... also crazy how bad the model is treating the mc like: sa, apology, sa, apology etc. like no wonder the mc doesnt trust your words cuz you literally said what he wanted to hear what you felt.... also this ends at chapter 5 for me cuz nah no recovery after that. like bro almost raped him. anyways only giving it 2 stars cuz of the art and potential....