
He knows as far as I know. I believe it was in chapter 18 when Yujin was drunk and horny
I think the "from now on" aspect doesn't necessarily mean that he's bottomed before (since this has been proven false and Aaron really did pop his ass cherry as the man said in Ch 18), I think it can just mean of Yujin's other hookups in which he topped. It's just a standard possessiveness line that could just mean that Aaron would be the only one who knows what Yujin looks like when he's having sex from now on

Ahh i see that makes sense thank you and yeah I just quickly reread and it was chapter 18 when he reveals it was his first time Aaron also mentions it in 20, 29 and this chapter with the (I copy and pasted do it capitalised wverthjng) HIS LEWD HOLE, HIS FUCKED OUT FACE, HIS HOARSE VOICE SCRAPED RAW FROM HIS MOANS...
KNOWING I'M THE ONLY ONE WHO KNOWS THIS SIDE OF HIM...
EXCITES ME SO MUCH, IT STEALS THE VERY AIR FROM MY LUNGS AND HAS HEAT CREEPING UP THE BACK OF MY NECK.
"I'm the only one who can see him from like from now on". You just said you're the only one who's him like that ie bottoming so "from now on" makes it sound like others have been but now it's just you. I wonder if it's a translation thing cause from now on doesn't fit