I think more than anything this conflict highlights that they're both already making a lot of compromises, the difference is that Jaeyoung is aware of that and can see how they're both making changes to accommodate each other but Sangwoo isn't seeing all that Jaeyoung is doing/all the ways he's changing for him. He just sees the things that still bug him and continues trying to restrict and control Jaeyoung to "fix" those things without acknowledging all he's already been sacrificing which understandably makes Jaeyoung feel unappreciated and hurt.
The texting thing is kind of complex, because I think how we communicate is a big part of who we are, so more than the other things this feels like he's trying to fundamentally change who Jaeyoung is and how he speaks (even if it's just through text) so I'm definitely not on his side with that one
same thoughts!
just to add to this conversation,
i think both sides actually have a point.
those who side with sangwoo think that it's just typing and a small thing to adjust, it shouldn't be difficult to change, so it's about effort in a relationship.
on the other hand, those who side with jaeyoung think that jaeyoung has already made enough compromises and as you mentioned, our communication style describes who we are, so it's about one's own personality.
it's not actually about how many compromises have been done, but how much change should one allow that would still keep their identity :DD

I kinda see each perspective and understand what they're thinking and their argument. What do you guys think? I'm kinda with Sangwoo with this one, although Jaeyoung do make some sound points. It's like rigidity/control vs flexibility/go with the flow no?
A compromise should be made, that I 100% agree on.