A lot can happen in 2 years. Also, that's actually a very common thing for someone with abandonment issues to do: separate themselves from the person they like the most because they can't handle saying goodbye. It's like a subconscious "if you hate me, it'll be easier on both of us" type deal. It's very commonplace among children when one of them is moving. They either avoid their friends, or get avoided until they leave.
Seriously, though. They need to get their groove on. Lol
Some people just can't see past their own problems and issues. No matter what, you have to be somewhat selfish to be happy. If that means you have to stand your ground and that hurts someone in the process, so be it. Never compromise your boundaries for someone else. It's never worth it and you end up giving more in the end than you ever planned to.

So he has to go to the military. So he spends his remaining time avoiding him?
Stupid.
They could have been fucking instead of arguing.
Also, everyone in Korea must do some military service. So why would this be so hard to say?