We tend to drink in destructive untruths and half-truths about God with the cultural water. A famous one is that God will not place on us more than we can bear. That is absolutely false, and the Bible nowhere says it. Throughout Scripture, we routinely see God placing more on people than they can bear, so they will learn to rely on him fully, deeply, and experientially. God's call to Abraham to sacrifice beloved Isaac, David's loss of an infant son, and then a grown rebellious one, Jacob's loss of Joseph --deep griefs all, and more than any human can bear.
A related destructive untruth is that God charts suffering on the course of believer's lives to "teach them lessons," as if God is some cosmic schoolmarm, with a huge ruler, just waiting to rap the knuckles of pupils that are dullards. This is an un-Biblical notion of God, and it is from the pit, designed to rob believers of the beautiful comfort that comes in belonging to God.
I certainly believe that nothing comes about by accident, and it is equally destructive to say of suffering, "God had nothing to do with this." The question is, then, what is God's purpose in charting suffering in the lives of those whom he loves?
God is at the bottom of the well of suffering. When all is stripped away, when life with its fleeting pleasures appears as the Vanity Fair that it is, when we are robbed of the comforts of the unpredictable plant, we discover that God is there, and that relationship with and to God is the all-engrossing thing. God plus nothing really is everything: everlasting joy and eternal comfort. Heaven would be grand if all it were was a big empty black room, with God and me in it. He is the all-entrancing, all-engrossing thing, the thing without which life is not worth living, and the One with whom even the hardest life is very heaven. God designs suffering to draw us close to his own breast.
It is true that God sometimes deals out suffering as a discipline for the sins of his people. In other words, sometimes my rebellion against God makes him withdraw his protection of me. But, even in this, God is not standing over and against me, wagging his finger. In fact, his discipline of me is a mark of his love --those whom the Lord loves, he chastens, and reproves every one he calls to be his child. God's discipline is not the discipline of the elementary principal, but of the loving father. It is done in the context of relationship. Even the extreme measures necessary to get the attention of some of his children --the handing over to Satan of the Corinthian offender, for instance-- is done out of love, "for the destruction of his body, and the salvation of his soul." God will bring his children back.
So, if you belong to God by faith in Christ, know that he loves you, and will never cast you off. You are his child, he is your father. That relationship is invincible, it is impossible to forfeit. Yet, if you stray from him, he will make life distinctly unpleasant for you until you return to his fold. And, if he charts suffering in your life, you need not fear, because he is pulling you to himself, and showing you that he is all-sufficient, and relationship to him, with everything else stripped away, is the fullness of joy.