All of us at one time or another have asked, "Why?" The psalmist's first word in Psalm 10 was "why." Often we ask because of our limited human understanding.
But God knows the end from the beginning (Isaiah 46:10). He wants the very best for our lives, and He has a perfect plan. We may not understand why until God has worked some things into our lives. In some cases, we will not know the answers until we get to heaven.
The Word of God says in Psalm 18:30 that God's way is perfect. This means that God's plan is perfect. All things are for our sakes (2 Corinthians 4:15). Romans 8:28-29 declares that "All things work together for good to them that love God, to them who are the called according to his purpose," that we might be conformed to the image of His Son.
God always has a perfect plan that He performs with imperfect people. We make imperfect decisions, and God does not interfere. Yet somehow He makes something good out of it by grace, love, and mercy. Time and time again, He allows things to happen. Sometimes it takes a lifetime, but guaranteed, in due season, God will reveal why.