I wouldn't call him a green flag too you're right, but he definitely wasn't a black one.. Going from being deeply obsessed to genuinely hurting and raping yujin is sort of a big jump in my opinion :/
People should stop labeling characters or real-life individuals using such simplistic terms as "green flag" or "red flag." There are nuances; we are unpredictable, complex, and exist in shades of gray—there is no such thing as absolute good or absolute evil.
Aaron’s behavior was progressive; I don’t know why his change comes as such a surprise, given that he always imposed his presence or his will upon Yujin—even when Yujin didn’t want it.
Where did people get the idea that Aaron is a "green flag"? He has been a questionable man from the very beginning—from his obsessive love for Jujin to the way he investigated every corner of his life just to keep him leashed like a dog. His love is intense, passionate, visceral—it almost feels violent. He spent his entire life longing for, and waiting to hear, that voice and see those eyes that had captivated his soul; he was consuming himself in a love that drove him to cross any boundary. It was inevitable that, sooner or later, his composure would shatter—that his facade as an unconditional lover would crumble the moment he could no longer maintain control.