All good things come to an end...but is that really necessary?

Why exactly must all good things come to an end? I mean, if it was necessarily to make room for better things, ok, that's great then but why is it that we expect, we know, if we are wise, that from the start of anything, it will inevitably come to an end? Should we not go into it with the shred of hope that somehow it will endure? Is it even possible for something to last? Should anything last forever? It feels like it should.