In your heart
There's a room where you lock away
All the times and the things that she said
And now red is blue
What was near is far now
Red is blue
Like a fallen star
And red is blue
Arthur didn't seem like he felt all the harsh things people said, he always seemed distant. It made sense, seeing as he was an island nation. He would snort at France when he said that he used to be so cute as a child, telling him those days were long gone. And of course, Francis simply thought that meant that Arthur had grown up.
He never stopped to think that England meant that he didn't see the care in France's eyes anymore, that France would not help him anymore, that they had fought over and over until the trust Arthur had as a child for the other was shredded and torn beyond repair. That he distanced himself so that Francis could no longer hurt him so badly that he would cry. That in doing so, he hurt himself that badly.
Nothing made sense anymore, so Arthur would go along with it, being as nonsensical as he could, an Alice finally fitting in with Wonderland so he wouldn't be scared. Giving up sanity to keep his sense of self.
All the things Francis said over the years did pile up, did create hurt, but Arthur always forced himself to lock it away. In his heart, his old self, the one who barely reached knee height, would pound against the locks now and then, screaming that he loved France, that he always would.
But Arthur couldn't deal with it. He could leave his old self like that. France couldn't hurt him if he did that.