The mark thing is so true like why talk about doing it once he wins a trophy and then just.. not
OMG WAIT I WAS LOOKING BACK AT COMMENTS AND SOMEONE SAID IT HAPPENED IN CHAPTER 50
I thought the same when I was reading that chapter, but then they show us the back of his neck 6 years later and there's no mark. And then I think that I remember them talking about how they wanted to do it during the extras, but that they were going to wait because of the upcoming surgery and because they wanted to clear it with the doctor first. Maybe the artist forgot to draw it in the scene where Yi-Rim was making his comeback...
This is just my personal opinion, but I wish omegaverse authors stopped making omegas run away from their partners either during or immediately after a pregnancy. At least this time it actually felt like it made sense with the protagonist's personality and his struggles, but using the same conflict twice was overkill.
That aside, I'm impressed by how this author handled the other usual clichés that we find in these type of stories (like the alpha having a past traumatic experience involving an omega in heat driving him towards escapism instead of making him an asshole towards omegas, or the suspected love rival actually just being Some Guy who genuinely admires the omega's career instead of thirsting after him). The characters, for the most part, feel well-rounded and multidimensional. The only thing that this story needed to feel completed was a mating bite scene. I usually wouldn't care that much about whether they mated or not, but there were several times where the characters themselves made it into a big deal and it feels like something's missing after finishing the story with not even a mark as proof that they finally did it.