I think that this is one of the hardest questions we face: if God really is powerful and loving, the way the Bible says, why do such terrible things happen?
God will stop all the suffering in the future. See, plucked from a choice of many passages, Revelation 21:4:
“He will wipe away every tear from their eyes, and death shall be no more, neither shall there be morning nor crying nor pain anymore for the former things have passed away.”
And it’s going to be soon, real soon. We’re just waiting for the time to be right. Revelation (ch 6:8-10) says that all the suffering cries out for vengeance, but God is waiting until enough people have been saved.
In the meantime, there are many different causes of suffering — sometimes caused by the deliberate maliciousness of other people, sometimes disease, sometimes accidents, sometimes natural disasters, while sometimes it is the unhappiness associated with an unsatisfactory relationship. This is God’s work:
“I consider that our present sufferings are not worth comparing with the glory that will be revealed in us. The creation waits in eager expectation for the sons of God to be revealed. For the creation was subjected to frustration, not by its own choice, but by the will of the one who subjected it, in hope that the creation itself will be liberated from its bondage to decay and brought into the glorious freedom of the children of God. We know that the whole creation has been groaning as in the pains of childbirth right up to the present time.” (Romans 8:18–22, NIV)
Suffering brings us to God. Not nice, but true. It was true even for Jesus:
It was only right that God, who creates and preserves all things, should make Jesus perfect through suffering, in order to bring many children to share his glory. For Jesus is the one who leads them to salvation. (Hebrews 2:10, GNB)
Use your freedom: choose to come to God. It’s the only way to see the end of suffering, but it will not be until God is ready.