chasing arc usually happen because reader hate the seme who treat the uke badly, so we want them to suffer to be fair
But both of them aren't toxic at all
even when Juheon wants to be alone, he never try to hurt Dohu first, and he stay single, he only reacts strongly when Dohu distrub his boundaries, when he with Dohu, he is loyal, kind and take care Dohu well
If I can get someone like Juheon who treat me well like he treat Dohu, I can't even think about hurting him, he just wants to be alone because he confused with his trauma and his own feeling being hurt by Dohu and his family
Of course what he did can broke the relationship, but he has the right to choose to be alone and leave the relationship
Dohu has never once pushed Juheon away. It was always Juheon who ran from him, ceasing all communication and not giving Dohu chance to talk. All this despite the fact that he was still in love with Dohu, not knowing that his actions had ruined Dohu's life. It would be a different story if Juheon no longer loves Dohu. Juheon will be devastated once he knows the truth. He really thought what he did was the best for Dohu, but the opposite happened.
Not necessarily a lot of BL’s will have a 2nd ML almost all. The audience doesn’t have to hate the Seme to get another 2nd ML. The author just tries to add more drama and or savior for the MC. Ofc we don’t want this mahwa to become toxic but Juheon is constantly pushing Dohu away because of his trauma. But he needs to come to a realization that he still does have feelings for Dohu. It’s getting exhausting mentally for both of them to play cat and mouse. It just sucks that when Juheon finally goes after Dohu we know Dohu will fold right away. We love that ofc but I personally want Juheon to show the same yearning effort for Dohu.
I see Juheon already know about Dohu suffering and he already try to help when he also wants to maintain boundaries because he has problem with his family and he doesn't want Dohu to get involved
He really wants to take care of Dohu at this point but doesn't know how to not break his boundaries at the same time
It's already different kind of suffering for someone like Juheon who like to take care of people he care the most XD
I agree with your point that Juheon is trying to open up more to Dohu. Ik Dohu is pushing boundaries which got them to somewhere but then looped back to stage 1. I think if he wants something with Dohu he needs to 1. Either handle his problems with family. (Which 100% I understand where he’s coming from and it’s hard) Or 2. He needs to realize his feelings for Dohu and express his needs of his feelings or tell him he needs time before he can be with him. But then the part where I’m saying Dohu needs a 2nd ML its not necessarily to make Juheon jealous but to make him realize that he wants to be with Dohu. And show him that Dohu also has boundaries and may wanna move on. That’s where the yearning part will come in because we all know the author ain’t gonna make Dohu commit with a 2nd ML. (Or they both could take couples therapy) ╮( ̄▽ ̄)╭
Even if the author add 2nd ML, it will be useless, you remember he doesn't even care about his friends from college and forgot the time he needs to meet them, he only care about Juheon, his friend even complain about it
if we have 2ML, Dohu probably will ignore him
And I will feel bad for the 2nd ML if that really happen XD

Bro we need a chasing arc from the top. The author should add another character that is interested in the bottom. But the bottom needs to stop chasing and slowly distance himself from the top. And when the top sees the bottom and his new (love interest) he starts to get jealous and comes back yearning for the bottom.