From then on, mountains and rivers no longer meet, lovers no longer talk about length, the past is clear, love and hate are casual, I am not afraid of the future, I do not miss the past, and there will be no future.
This sentence expresses the author's sadness about parting and his expectation for the future. It means that the past has passed and is no longer important, but the present and the future are the most important. Stop talking about the good things or regrets of the past, stop being troubled by them and start your life again.