He had no idea how much he meant to him.
He didn't know that he would be so humble and helpless after leaving him.
"If we meet on a rainy day, let's break up on a rainy day."
Before leaving him, he was a little uncomfortable with the life around him. It was obviously a place he had been in since he was a child, but he felt very strange.
He overestimated his abilities and underestimated his stubbornness.
Concept: Simple and pure love