It doesnt, if anything I think it makes it stronger argument for the couple cause they fell for each other without the mark's direct influence (minus all snakes like the scent or w/e).
It's more so just some anxiety cause it does shake up the foundation of how they got together (and what they've been dealing with for a long time, like Ivan's frustration on not being able to satiate Hen's flares, etc) + the real marker is someone Hen has history with and probably still has some lingering affections for, although he's been good at being faithful to Ivan.
If it is revealed soon that it was Alek, there ~may~ be the presumption that Alek should be the one to help Hyun's with his flares until the week is up, which due to the sexual nature of it...is gonna just make things super awkward.
I will say though, if Alek knew the whole time he was the marker and never said anything; that makes him a huuuuge asshole imo. That mark gave Hyun a lot of unnecessary pain/discomfort, made work environments stressful (like the meetings with the snakes) and just general confusion. I'm assuming/hoping that he was drunk that night too and didnt remember but I have a feeling he does remembers and just keeps the fact to himself. Maybe as a measure to get back at Ivan, but that's probably reaching.
Ivan was a womanizer + horndog in the beginning but he was always willing to help Hen with the mark stuff and was responsible when he believed he was the marker. At least to my memory.
I don’t understand why people are making such a fuss about who marked him. Honestly it’d be better if Alek was the one who marked him because that would mean Ivan and Hyun didn’t fall in love because of the mark but because they actually like each other. Either way it shouldn’t actually matter who marked him in the grand scheme of things.