About the adult but kid thing, I agree. I wish the "reveal" that he was the lover was at a later date. Like yeah sure, reveal he's from the future so they have a reason to talk but maybe have the ML slowly come to the realization when the MC is 18 lmao like maybe it's goes from "hey he's a suspicious kid" to "hey I think this kid knows me too well" to "hey he's from the future and knows me" to "who am I to him" gradually over the years and eventually "he was my lover from the future all along". Kind of crazy they skipped the first dozen steps.
Unfortunately, that ship has sailed.
However as for US thing, Id disagree. the MC would absolutely have unalived himself in the US (seeing his last lines to minhee was uh, least to say, very concerning) since it mirrors the MLs words when he was suicidal (prolly a callback). If he left, I honestly do not see that route ending in nothing but a BE. I think the author set up the US thing to be more of something that "mirrors" what the MC did for the ML. It's pretty good writing imo for the most part.
I disagree.. first of all, if he is to leave, I'd want it to be something he does of his own accord not bc he is being blackmailed. Even if he had gone, his mental state would have taken a huge hit. Looks like now he is ready to make that decision, since he called his brother or somehow let his brother find out where he is albeit he did it for Taehyuk, but it was his decision.
And from the way the brother talked to his mom after Hangyeol ran away from airport, makes it look like she is emotionally/mentally abusive or super controlling towards the older bro and most likely he is doing the same to his younger bro bc it has been normalized for him.
I don't know why the author didn't let him leave for USA ! I mean it could have been SO perfect so his body grow old enough for them to be reunited later. Yes he has an adult mind but it's still make me feel uneasy to see "cute" scenes when he is a child... Go study something for some years and come back at 18 ok ?(￣∇￣")