When people talk about a "good hurt", this ending is what they mean. I don't know if I'm now sad, angry, or disappointed. Maybe all three. Either way, this is one of the very few manga I can confidently say had a profound effect on me, but, part of me wishes I hadn't read it at all.
For all their flaws, mistakes, and frustrating impossible nature, I will miss every character in this story deeply. Goodbye everybody, and goodnight, punpun.