
In most omegaverse stories, that's the case. But some authors like to change things up and make their own rules. (An example being in Love is an Illusion, where Hyesung of Dojin form a pair/bond by emptionally connecting, rather than biting the neck)
Also, I forgot if this was stated in the manhwa already, but the thing about omegas marking alphas was explained in the original novel for Kiss Me, Liar
Imo it's refreshing to see the roles reversed for once =)

No problem =) I know the omega has to bite the alpha during sex, but I'm fuzzy on the details since it's been a while since I read it. It might have to be specifically during rut, but I'm not sure.
Can't remember the exact number of chapters, but I want to say it's around 50-ish? (+ epilogues)
Apparently someone has worked on translating the novel (not the version I read). https://www.novelupdates.com/series/kiss-me-liar/?pg=3
It's not complete, but they look like they're going fast =)
How did he mark him? And does that mean that he is his official partner?