If God works all things according to the good of those who love Him, why do some believers suffer and die? It is helpful to remember when answering hard questions like this that it is always gain for a Christian to die. God will sometimes override the good thing of temporal provision to bring the better thing of going to be with him. This is not a surprise, because no person escapes physical death.
But what about untimely death? Think about the thief on the cross suffering and believing in Jesus. His encouragement in the face brutal pain was, “Today you will be with me in paradise.” He was dying but good was coming. With failing lungs and a heart of faith he grasped the better and breathed his last.