Although God loves us, He allows us suffer. Actually, a better way to put it is this: Because God loves us, He allows us to suffer.
Suffering, though painful, is one of God’s gracious ways of pulling us away from our self-love and more towards loving Him. A life of ease just doesn’t sanctify us like suffering. Our hearts, as the hymn says, are “prone to wander, Lord, I feel it. Prone to leave the God I love.” The prickly hedges of suffering help us not to wander far from God’s path.
John Calvin says it this way:
[W]e see not how necessary that obedience is, unless we at the same time consider how prone our carnal nature is to shake off the yoke of God whenever it has been treated with some degree of gentleness and indulgence. It just happens to it as with refractory horses, which, if kept idle for a few days at hack and manger, become ungovernable, and no longer recognize the rider, whose command before they implicitly obeyed. And we invariably become what God complains of in the people of Israel—waxing gross and fat, we kick against him who reared and nursed us (Deut. 32:15).
The kindness of God should allure us to ponder and love his goodness; but since such is our malignity, that we are invariably corrupted by his indulgence, it is more than necessary for us to be restrained by discipline from breaking forth into such petulance. Thus, lest we become emboldened by an over-abundance of wealth; lest elated with honour, we grow proud; lest inflated with other advantages of body, or mind, or fortune, we grow insolent, the Lord himself interferes as he sees to be expedient by means of the cross, subduing and curbing the arrogance of our flesh, and that in various ways, as the advantage of each requires. For as we do not all equally labour under the same disease, so we do not all need the same difficult cure.
Hence we see that all are not exercised with the same kind of cross. While the heavenly Physician treats some more gently, in the case of others he employs harsher remedies, his purpose being to provide a cure for all. Still none is left free and untouched, because he knows that all, without a single exception, are diseased. (John Calvin, Institutes of the Christian Religion, III, viii, 5. Logos users click here).