Is there anything good in goodbyes?

Is there anything good in goodbyes? What do yo get when you say goodbye? What happens after that? If I say goodbye, I always ponder if I would ever see that person again, if they will return, or leave permanently. But there is still that desire to see that person again. (Of course if you hate the person thats a different matter.) Think about it. If you ever have to say goodbye make it the best one you ever had so far.