People come into your life for a reason, a season, or a lifetime. When you figure out which one it is, you will know what to do for each person.
Just because you meet someone and you establish some sort of relationship with them doesn't mean that they are exactly the people you should relinquish as life long friends. As many of us have recognized by now, life is full of different seasons. As people to continue to progress we have to continue to set new standards and new rules for ourselves.