A highly imperfect analogy:
A father allows his child to pour himself a glass of milk. The child can’t handle it, and ends up pouring milk all over the table and the floor.
Now, did this HAVE to happen? Of course not. The father could have poured the milk FOR the child, and the whole mess need never have happened. So, was the father malevolent? Was it his “will” that the child spill his milk? No! It was the father’s will that the child pour the milk into the glass without spilling a drop. But the father allowed the child to try something he knew that child might not be able to do. Epicurus could argue, then, that the father “allowed” this accident to happen. But would that make him a cruel sadist? Hardly.
When you give a child a chance to act on his own, there’s always a risk he’ll fail, and that the result will be disaster. But you HAVE to give that child a chance, or he’ll never learn and he’ll never grow. The alternative is to raise a helpless, dependent child with no freedom and no mind or will of his own.
End of analogy. Back to the problem of suffering. MOST human suffering is caused by humans. Most of my own suffering in life has been my own fault, the direct result of my own choices. Most of the rest of it has been the fault of other people, the direct result of others’ actions.
In these situations, to ask “Why didn’t God prevent this” is really to ask “Why did God give us free will?” Free will comes with a price, and it can be a terrible price. I can hurt myself. I can kill myself. And worse yet, I can hurt or kill others. If I elect to get drunk and drive fast, I might kill some innocent bystander. And God is not going to save me (or the bystander) from the consequences of my immoral actions.
So… in that hypothetical case, is it “God’s will” that I get drunk and kill someone? No- but God isn’t going to use magic to force me to be good.