You have to understand what people are actually mad at.
You're making a good point about Aaron never actually being the typical green flag guy but I'm sure the discourse here is about how the artist chose to portray the problematic aspect.
The way the artist draws the rape/non consensual parts are romanticised and made to look almost the exact same as the parts where Yujin enjoys being with Aaron, and I think there needs to be a line drawn between the two.
I don't wanna see a blushy body on yujin when he's obviously not enjoying what's happening to him, that's fucked up.

I get it, rape is not cool and there are better ways to improve the plot without adding that trope.
Honestly, what did Aaron expect? That Yujin comes crawling back to him after doing all of **that**?? But also, did y'all really think Aaron was a green flag? If you look at his backstory in season 1 or 2 (don't remember exactly), it showed that he was a sociopath and grew a successful career in acting since he learned to imitate people's mannerisms and emotions at a young age. So, obviously, Aaron is morally gray, dare I say closer to a black flag based on what we saw happen since the beginning of his relationship with Yujin.
But, this story still ain't over so we have to wait and see what happens next. I genuinely don't wanna lose hope in this series because it has potential in my eyes and I low-key want to see Aaron learn that what he did to Yujin was too far THE HARD WAY (let him get punished for it