Each daydream can have a different ending, and if it is not good enough once, it can be overturned and tried again.
However, everyone's life has only one predetermined ending. It is unknown at the moment, but it is already waiting for you to go through it in the future.
I met many people along the way and stayed for different lengths of time. Regardless of whether you can remember the smile of a passerby in the end, he will definitely have a shadow on your life.
It's impossible to assume "what would my life be like if this person had never appeared."
Just like between them, there is no possibility of each other not existing.
It's just that this projection is too profound for them.