He said, "All this time, I had worked hard to have J.Y. Park listen to many of my demos and to get confirmed by thirty monitoring agents. This song is something that I made starting in December last year and mulled over a lot."
Jung Chan Woo queried, "What happens if [the agents] say that sixteen songs are good, but J.Y. Park says he doesn't like them?" Jun.K and Park Ji Min replied, "They're still good to go. The producer's influence got weak. The producer also got turned down a lot. If they slouch, he thinks that [the song] didn't go through. If people don't like it, you'd think he'd get disappointed, but he would say, 'It's not great?' and immediately go away to work on it. He has an amazing mentality."
You gotta get used to constructive criticism as an artist, and he's gotten a lot of experience with it!