I think that the thing that mainly makes Ryou jealous is that Shion implied that Nao is interested in Shion in romantic sense. He might have meant that as a friend but was (probably intentionally) cheeky about it and said it in way that could be misunderstood.
It seems to me that the reason Oto doesn't feel jealous is that he's spoken with Shion about the relationship Shion has with Ryou and from that Oto has seen that Shion is not interested in pursuing a romantic relationship wit Ryou. And Ryou wasn't serious about Shion either.
I don't think anyone is saying that it wouldn't be okay for Oto to jealous tho and in my opinion it just seems that Oto's not jealous person. I'd say it is completely fine for Ryou and Shion to work together as long as Oto doesn't tell them otherwise... I don't think I'd feel jealous if I were Oto tho, unless I had reason to suspect that they'd start cheating. In this specific case I'd say that's unlikely, (at least I don't get that vibe at all from readers point of view).
Well, at least that's just how I saw it... ╮(￣▽￣)╭
Yeah. I feel the same. It's the context of the relationship between the three. It's not like the fbuddies thing was a secret anyway. It also helps that the tone between Shion and Ryou is very casual/professional depending on the situation. There's just no deeper intimacy there to be up in arms about it.
I totally agree with both sides like if there’s no bad blood and I’ll intentions (as we know for sure) I can’t be jealous, butttt at the same time… you right slurp just me as a person, I would always have it in the back of my mine that the seme ate my photographers ass before mine (lol) and that they had a very sexual relationship before. Also the seme had originally mistaken me as him I would low key feel weird but ehh it would’ve been my choice to stay or not.
Maybe it's only me but I don't like how Ryou and Shion can work together while knowing the feelings of Oto. Like, Ryou is jealous about Nao but Oto can't be jealous about Shion? While they were fbuddies and it seems like Shion likes Ryou? Like, are they not uncomfortable with the situation? Or it is normal and I'm the only one overreacting. Also, Shion used to live in Ryou's house. He still has a spare key and he's the photographer of Ryou. It's like, is it normal? If Im in Oto's situation, I won't really like it. I get the working part but...is'nt it awkward? Its like they're showing that Shion and Ryou are fbuddies like they're just eating together. But they eat each other ass anyways. Idk lol