Ikr, there are certain tops that I can tell who will flip and go crazy (for example Yoon from 'Gig of the Day") but it somehow makes me feel Aaron won't do that and the author won't ruin it for us. But we can never really know what's gonna happen so I'll trust this comment and my instinct and hope I don't have to eat my words
Yess! I feel exactly the same way!
I was literally gonne use Gig of the day as an example here.
With that story, I had a bad feeling about the ML from the very start because his 'nice' actions always contradicted with his thoughts.
Aaron is definitely possessive too but feels.. safe? idk xD
But like you said.. We never know what the Author might do, so I'm nervous. I feel you.
Gig of the day has turned towards a bad way but I always predicted that because the ml was so fucking controlling and he never once considered Yeomin's feelings. I don't usually read stories that have generic plots of "small petite uwu bottom with daddy's debt and rich ceo red flag top" but I read gig of the day because I love how independent and head strong Yeomin's character is. The ml just ruined the story for me and I haven't read it for the last few updates.
I just WISH and HOPE Flashlight does not take that turn too and I might have to ultimately drop this too because I really like both Yujin's and Aaron's characters and their story so far.

Unpopular opinion :
I feel like Aaron would never hurt yujin, especially if he finds him again.
He's angry and frustrated, sure, and even he himself might feel like he'll flip out if he sees Yujin again, but I feel like the chances of that happening are low and it's just his desperation showing. (Y'all are scaring me though )
I mean, we saw his reaction the last time Yujin got hurt after Aaron already realized his feelings : He doesn't want to see him hurt and I feel like he'd do anything to PREVENT that.
Especially since he knows Yujin didn't leave because he 'doesn't love him' or wanted to fuck him over.
Yujin left BECAUSE he loves him and wants to keep him save. He probably didn't think it would have this much of a bad effect on Aaron.
I hope this comment won't come back to bite me in the ass and that it ages like fine wine instead of milk.
I will be very flabbergasted and disappointed otherwise