Probably in future chapters, as they grow closer by being intimate, MC will be more in peace with what happened to him. Even if he presented by fate and not by exposure, he still was scented without his consent, tying him up to the alpha for life. Not that the omega would seek another alpha because he resents his gender, but by scenting him, the ML took aways his choices and this story showed us that he's a very proud individual with very complex feelings about his second gender and the big changes in his life (family, career, sports, social, etc).
But of course, they will understand each other some day because this story is about finding soulmates no matter if they're a/o or a/b.
I pointed out what wasn't correct in the post.
What I'm mainly putting forward for reflection is that the fandom is assuming theories as if they were truths presented in the manhwa, while very little has been revealed so far... Questions without an answer yet:
1) Who mutated the uke?
2) Was it accidental or intentional?
3) If it was intentional, why did they do it?
4) Why is the uke always angry? Possibilities:
- Anger towards Su-ah for causing his mutation
- Envy of Su-ah for him being an alpha
- Gender dysphoria
- Internalized prejudice regarding his own gender
- Anger at being dependent on Su-ah
- Hurt ego for not being in the gender "caste" considered the "best" in this universe
- Some of these options combined
Other questions that the story hasn't explicitly answered yet:
1) Why, after the gender change, does the uke no longer want to marry the seme?
2) How do the other family members deal with the uke and seme being the first alpha/omega in their families?
3) Does the uke really no longer like the seme, or is he deceiving himself?
4) Did the uke truly love the seme in childhood, or did the "relationship" only make sense if he was the alpha?
In short, many questions. The story is only just beginning, and assuming theories as certainties is a mistake made by part of the fandom.
I agree but what I pointed out was what's confirmed which are Alpha scenting him without his consent and Omega's complexities and feelings. This omega is very vocal about them so even if we theorize or make assumptions, his reactions were very obvious and visceral and now he's bargaining because he needs the alpha against, what it's apparent from his dialogue, his free will but again he's in bargain mode. And of course because he still has a soft spot for him with or without the influence of alpha's characteristics that make Omegas infatuated. His anger is not just a straight answer because of his thoughts and his dialogue with the alpha as the story showed us. It's all that you mentioned, combined, because he's that confused, frustrated and angry.
There're only 8 chapters and this author is kind of direct in their storytelling but she could throw a curve ball and later show us that the omega can react to other alphas without feeling sick or being in heat or fall for another omega. Who knows. And maybe the narrative can be questioned and not to be trusted but the truth is that Su-Ah did scented him because of his possessiveness, he's showed his inner thoughts, and continue stalking with the excuse of being near in case the omega needed him when it's always about him not wanting the omega to be infatuated by other alpha and taken from him. Those were his words.
We can theorize about the past but in the present, plus adding those flashbacks, we can point out that the only thing they truly wanted was to be with each other in way or another but Su-Ah forced the bond by imprinting him and that's why, even if he wasn't the one who forced the transition, he was the one who abused his power and took decisions that weren't his and changed what was already a very difficult life for the omega.
Hopefully, in the next chapter they will have a more civilized conversation and clear some things before they get intimate.

There's some confusion between two different moments in the story that's hindering many people's understanding. 1) Childhood moment: the issue here, which many people are saying, is that Su-Ah mutated the dark-haired boy, BUT THIS IS NEVER STATED IN THE STORY. This is just a fandom theory. It could be that the uke mutated because of his family members (who are all alphas and mutated him intentionally or accidentally); it could be that it was his destiny to mutate regardless (what raises this hypothesis is the scene where the daddy says that maybe the dark-haired boy was actually Su-ah's omega...it's as if the pheromones of the two protagonists formed a DNA); it could be that another character, not yet revealed, mutated him; it could be that Su-Ah actually mutated the uke (accidentally or intentionally). The truth is that at no point is it confirmed who mutated the omega. Perhaps the omega assumed it was Su-ah, but we're not even sure about that, because the story hasn't explicitly revealed whether the omega believes Su-ah mutated him. The fandom is assuming that the uke's irritation with the blond was for that reason, but this isn't clear in the work. 2) After the brunette reveals himself as an omega, it is explicitly stated that Su-ah is covering him in pheromones without his consent. Of course, this isn't correct, however, there are some explanations for why he did this, and the story doesn't yet fully confirm it: he may have done it to protect the omega, after all, he's fighting in an environment surrounded by alphas and doesn't wear a collar; it could be that, since they swore to marry, covering the omega with pheromones made sense in the alpha's mind (many people think marriage gives permission for certain behaviors - although, obviously, this isn't correct); it could simply be selfish possessiveness. In short, what I'm trying to say is that the story is still in its very early stages. Many elements are yet to be revealed, and these could completely change the understanding of the plot. It's still too early to judge either of them regarding the omega's gender change and the resulting actions. We need to wait for new chapters and not assume theories as truths.