I read this on another reaction and I'll post it here because it seems like a great explanation! "My theory is that these are all different events that occurred to him in various timelines of his life: he was a child to his parents, a friend in a group out partying, a boyfriend in a turbulent relationship, and then a husband with a beautiful family. Throughout, he felt like he never fit perfectly into any of these roles. In his journey of self-discovery, he encounters another human, Kim Minha, who is as lost as he is in the maze of societal roles and expectations. However, after they have a conversation on the couch, he realizes that it's not just him; this is the reality for most people, and life is never going to feel perfect. Cut to him being transported to these scenarios again, but now he is happy because knowing he is not alone in the journey makes him appreciate life and its imperfections more. In the end, it feels almost like an enlightenment where he is freed from the shackles of pursuing a perfect life and now understands the true meaning of living. You see him walking through the forbidden door with Kim Minha, both now happy and content."