I'm sure that's it! Like it's a scheme because Tae joo is in love with him and not with the omega brother. Or he likes the beta but since he's not an omega, he prefers to be with his brother so he can have a family afterwards but finally he realizes that the beta brother is better
That was my guess as well, glad I am not the only one who caught on.
I read something similar – though it was hetero manhwa – plus, I heard it's a short story, which means there's no room for more drama, so the possibility of Heewon being in on that is big
Lol, yeah, Taeju getting in right after Heewon left is what's making it more suspicious
It'd be crazy if the brother and Taeju were only pretending to date, hence why he kept dragging Heekyeong to their quality time together