
I'm also in that age range and...it depends. First, they're like 23-25 if I remember correctly, and second, they see each other every single day. Many people usually fall in love/have a crush pretty easily and THEN build love as time goes by, but it's usually when you're already together, otherwise you're just orbiting around someone for years without crushing on someone else or having a partner? I don't know, but that's pretty wasteful to me.
Also, I think he said that because a) He's never actually fallen in love before, and b) Because his love interest is a man and he used to be extremely homophobic.
I've been in a relationship for years and I also thought "omg I've never fallen like this in my life" at first, and now I keep thinking I just love him more every day. It's pretty normal imo.

I can't blame either of them. Jaehyuk never fell in love before and Garam had a traumatic event that made him extremely wary of getting into a relationship, so getting that close to someone else and seeing them almost daily is something they were just not ready for. This is just how things look when you didn't give yourself the opportunity to emotionally mature relationship-wise.

Well you raise good points. They are not emotionally mature. When we are older usually we get to understand someone you know for a while will probably not be a part of your life in the long run, so there's no point losing sleep over them. Also, I think the author didn't do a very good job showing the flow of time. They make up and break up every two hours, we end up getting the feeling it's been at least a year
this whole time it’s been less than 3 months ??? he’s like “i’ve fallen deeper in love than i ever thought was possible” and y’all met less than 90 days ago