Basically, Jinhwan's a person who cares too much about his friends and gets driven crazy all the time about how two of them find it so difficult to profess their undying love. But Junhoe and Jiwon would always be bad at emotions, and it would be no surprise to Jinhwan if it took a good few years for them to properly confess.
Which is exactly what happened.
Jinhwan really didn't know how he hadn't given up on them yet.
