I'm happy this didn't turn in to the classic "seme thought uke was cheating on him"

IA.

I also I don't think Taehan ever thought that Doyun would cheat, more he was scared that another alpha would attack and try to mark him. And that's the difference. Taehan isn't written as being self-centered because he's an alpha (and that Doyun should fall at his feet because his dick is so mighty). He cares for Doyun because he likes him and he knows that as an alpha, he has a duty to protect him.

Cheating like that is about ownership and Taehan never acts like he owns Doyun (as if Doyun would accept that). He's always respectful and that's why he's the One.