Now if we are always falling back on these 'if-it-be-Thy-will prayers' we are debasing this most well known prayer promise of the apostle John, and making it a prayer 'let-out', a useful carpet under which we can sweep all our unanswered prayers. We imply that what he is really saying is this: 'And this is the lack of confidence which we have in Him, that unless we happen to ask according to His will, He will not hear us, and we shall not have our petition.' So the promise that was intended to confirm our faith serves only to cover our unbelief and to confirm us in our state of weakness, in seeking to prevail with God.
Sometimes the blessing is in the prayer not being answered.
God is just as merciful in the things He does not allow, as He is in the things He does.