The best response to pain (chronic or otherwise) is love, not anger. Yet anger comes so easily to some of us when we perceive the suffering of our loved one as unjust and unfair. Then that anger hurts the one we care about so deeply, and the cycle repeats and deepens the trauma. Pain leads to anger, which leads to guilt.
"Love is patient and kind," said the Apostle Paul. Anger, or at least rage, is never patient and kind, but is a manifestation of the flesh, the sinful part of us. Yet God is still there to forgive and restore, amidst our brokenness.