And God will wipe away every tear from their eyes; there shall be no more death, nor sorrow, nor crying. There shall be no more pain, for the former things have passed away.”
(Revelation 21:4)
In this life the pain of separation from the death of loved ones or when they move away causes the most grief. If we didn’t experience this pain on earth we would not be able to fully appreciate the removal of these tears in heaven. To appreciate Heaven’s best we must experience Earth’s worst.