How can suffering coexist in a universe with a perfectly good and all-powerful God? We can blame human free will, if we wish, but that does not remove the difficulty as to why God, knowing that men would use their free will thus, did not either refrain from creating them in the first place, or else ordain the most optimal outcome that He could engineer.
If all God’s judgments are remedial, and are employed to bring “many sons to glory” (Heb 2:10) then there is no mystery why He would allow a finite season of suffering (in this life, and possibly the next) to prepare His children for infinite eternal delight – both to themselves and to Him.