When does the big dream refer to the song?

When did the big dream come? This song tells a sad story that I can't love. When is the big dream? The meaning of the song is: life is destined to go through many tests, and you may get hurt on this journey and forget your original heart. I hope to be with each other in those difficult times, tell each other about the past and get to know each other better. This is the simplest and most affectionate confession, as long as you are with each other.