Write about break-up is something subjective. Anyone who has faced that moment, could describe it in different ways, not only for the situation but the feelings.
This Glee's episode try to carry us to that different situations and show us that sometimes something that we found interesting in the past could be annoying in the present.
Obviously, the kids has grown up and new objectives has appeared. We can't blame Kurt for not being interested in Blaine's achievements. For someone who works at Vogue may be won the school's elections is silly. But, also, we can't blame Blane for feeling alone and abandoned.
I believe that "The Break-up" is the deepest episode in Glee's history. Every story has differents edges and these are shown through one of the best script of the series. Maybe Rachel and Kurt's story are the most powerful but all the episode is perfect: music and acting.