ok, darlings. I'm gonna say this and I'm serious, please read all the story again, slowly and carefully.
Sumi has a strong heat that even can make him beg for sex (Utou is the one who said it), has money issues, he usually doesn't rely on people, the fact that he was gang raped actually made him feel he couldn't count anymore on people (and you could tell by the way he is and how he was living his life)
The one who made him able to trust in people again was Utou and when that happens, he gets sexually assaulted in a way that makes him see that no matter how hard he works, for others he will be just a sexual object; this struck his beliefs and his beliefs were all that he clung to after he was raped at 17
Shiratori saving him and being a friend of Utou made easier for Sumi trust in him
Sumi never intented to be paired with Shiratori. Shiratori deliberately stayed so close to him when Sumi was in heat and emotionally fragile to make him feel worse with his desire for an alpha and his longing for a man who didn't love him (since he thought that Utou loved Karasuma), mentioning Utou at that time was nothing but salt to the wound
Sumi trusted in him like a friend but he was used since the beginning like a cheap doll to hurt the only person he cares about, Shiratori shares some behaviors with sexual predators and abusive lovers, and yet there's people making fun of him or saying that he deserves this
Maybe the omega in Shiratori's memories dumped his ass after him not getting the job, or maybe he was forced by his family to bond with another alpha because they thought that Shiratori was not worthy of belonging to his family after having his job oportunity snatched by a beta
the one who is smiling with Shiratori and then we can see his back with a bite in his nape
http://www.mangago.me/read-manga/kurui_naku_no_wa_boku_no_ban_beta/uu/aef4f166b58d3be52672b100fe5f26f5_chapter-1/pg-21/
http://www.mangago.me/read-manga/kurui_naku_no_wa_boku_no_ban_beta/uu/ibx_chapter-3.2/pg-25/
utou was always plan A is his head, but because of the misunderstandings he tho his feelings were one sided- makes sense- so he wanted to not burden him. the only reason he is still with the alpha is because of the way it was handled after sumi and Utou kissed. so it was thrown out there, lets stop this, and I hope for you to be happy with alpha. SO EVEN IF EVERYTHING WORKS, HE WAS ALWAYS PLAN A. and sumi isn't the type to go to Utou and ran back to him, the while issue was stop burdening, so he would think that he would be burdening him again
I hope I make sense
I know he loves Utou and he never loved Shiratori, they don't even sleep together and he is delighted that nothing happened between them. But he also decided that he wants to make things work between them and now he is crying. I really want to know what he is thinking on right now. In some way or another, all three of them are pitiful.
I understand your point. once I read a oneshot where I don't know if it was because of the lack of pages but it seemed like the girl had stayed with the protagonist because the love rival was bad. But I think that here Utou and Sumi weren't ready for a relationship, even without the bite mark, cause they weren't able to fight their fears and doubts, they would may have ended up breaking up really bad if they have became a couple at that time
I belive that that's what Sumi is referring to when he ask why they can't choose, not to the lack of options but rather they feeling unable to choose because their lack of confidence in taking that decision
Someone knows it? I know that Utou has 30+ and I used to think that Sumi was 22, but I was remembering what I had to investigate once about the educational sistem in Japan, and it hit me that he could be younger
I don't know exactly how old Utou is, but he and Sumi are 12 years apart
you can see a comparison of all the characters here :) https://harmonia17.tumblr.com/post/179804506257/tinyrambling-source-the-age-difference
Why a lot of people hate Sumi? I know that he did something that hurt Utou, but you know what? Utou was a coward, he didn't say his feelings when was the right chance, he knew the other guy had bad intentions against Sumi and didn't warn him, he pried in Sumi's personal info but didn't try ti talk with him nor make a real (emocional) bond with him
And there's also what the other Omega said to Sumi about "don't destroy Utou", Sumi couldn't avoid to think that he was causing trouble to Utou, and he didn't want to be a burden to The one who was kind to him
Sumi felt that he had nothing, that he couldn't keep depending on Utou anymore, and everything was too exahusting. He was being stupid, inmature and selfish, but can you really blame him?
That’s where I don’t agree with the use part. Shira offered his helped. The night of the bond he explained to him why he is going this route, he didn’t force him and he was being honest. He didn’t manipulate his feelings and he would have totally accepted if shira agreed not to do it. But they both consented (〜 ̄△ ̄)〜


it just hit me the fact that, in a way, the ones who support sumi are feeling the things from Utou's perspective and the ones who support Utou are feeling from Sumi perspective
Not completly but in a way. Fight me and I'll explain (。・ω・。)ノ
REALLY. explain sis? cuz I'm confused (⊙…⊙ )
ok, this is about their relationship and not the general situation, that being said... let's get started
First with Sumi, he knows that Utou has such a big heart and that he was heartbroken because an omega, wich made Sumi try to stop dependig on Utou, cause he was feeling that he was taking advantage of Utou and that he (Sumi) totally didn't deserve him (Utou). But then Sumi actions end up hurts Utou and Sumi feels that everything is his own fault cause even when Utou actually loves him, he couldn't make the right choice (hence Sumi thinking that he betrayed Utou)
Does ring a bell to you ?
Now Utou, he knows that Sumi always tries to deal with everything for himself and also knows Sumi's past, which makes Utou want to take care of him and not press Sumi (partly because of that, Utou avoided confronting Sumi when he should)
After the bite mark, Utou can see his mistakes and how they made Sumi feel, that's why he says he is not disappointed in Sumi and can understand him (like those who support Sumi)