As long as life is a little green, what does it mean to have no sadness but love?

You just want to live a decent life, don't, don't be afraid of being cuckolded by others. So this is usually a joke. Some people say that as long as the object changes quickly, there is no sadness but love, which is one-sided and curious about new things. When one day you really meet something you like, it's like a moth, willing to spend a lifetime together. Even if I know that the ending is sad, I am willing to be fooled again.