The Torah informs us that when Hashem punishes us and drives us out of the Land of Israel into exile, leaving us to the mercy of the nations of the world, it is not out of disgust or repulsion, or an attempt to destroy us. It is a method of discipline, as a father disciplines a child who runs into the street in the path of an oncoming truck. The child needs to be chastised in order to keep him from harming himself in the future.
For this reason, the month of our greatest calamity, the month in which the Beis HaMikdash was destroyed, is called “Av.” It reminds us that we have a Merciful Father in Heaven, who cares enough about us to punish us in order to prevent us from committing spiritual suicide.
(Rav Zev Leff)