It is not possible to see now.
But when we are present with Him, we will know why. We will see how and we will realize how it all fit together. In the meantime, He is preparing us to be with Him for eternity.
It is easy to loose track of the eternal picture and merely concentrate on getting over the next high slope. There are circumstances and heartaches that seem to absorb any energy whether physical or otherwise. Some seasons are rough to the extent that getting through the hours seems an insurmountable feat.
Yet, He has only designed and delivered and allowed the best.
It will be worth it all, when we see Jesus.