This sentence means that once the opportunity to meet is missed, it becomes very difficult to meet again.

The sentence "Mountains do not meet each other, it is easier to say goodbye than to say goodbye" expresses a cherishment of encounters and reunions in interpersonal relationships. In real life, this sentence is often used to express longing for relatives and friends, as well as emotions for those who are difficult to see each other again due to various reasons. It’s a reminder to cherish the time you spend with others because life is full of uncertainty and we can’t predict when we’ll be able to see someone again. Therefore, this sentence also encourages people to seize the moment and cherish every gathering.