God did not cast them out of the Garden. They distanced themselves from God when they sinned. This distancing is the natural result of sin. Nobody can come into the presence of God without holiness. We see how Adam and Eve hide themselves behind the bushes. We see them trying to cover themselves with leaves. Thats what sin does to us. It distances us from the presence of God.
Sin is not an act but a condition. The condition where man looses his capacity to know, love and serve God, and also his neighbour -if not fully. The acts we commit are the fruit of this condition.
Are we not then, confessing only the fruits and not the condition itself!
We also see how God covers Adam and Eve with animal skin. We can assume that, an innocent animal had to give up its life to cover them. In the act, God also covers them with the blood of the animal. This is probably how Cain learned the kind of sacrifice that would make him righteous before God.
God did not intent man to labour or suffer pain. Labour in the field and labour in child birth are also the direct effects of the original sin.
God the father sent His only son to save us from sin and the suffering it brought us. Through baptism God removes the effects of the original sin, and sets us free. The liberation nevertheless is experienced only when the grace received is applied in real life in faith. This means we are set free only when we live according to the word of God/Spirit.
We should not blame God but ourselves for the cruelty, suffering and disasters we see in the world. But God in His mercy turns even these suffering for our good. The innocent sufferings of our brothers and sisters in many parts of the world causes God's grace to fall abundantly. It is because their sufferings is joined with the suffering of Christ just as it is mentioned in Paul's letter to the colossians "Now I rejoice in my sufferings for your sake, and in my flesh I complete what is lacking in Christ's afflictions for the sake of his body, that is, the church" [1:24]
That is why it is said "But where sin increased, grace increased all the more. [Rom 5:20]".
The suffering will cease and peace will be established when all of humanity believes in Jesus Christ and orders their lives according to God's word. Or at the end when the Lord gathers the wheat and leaves the weeds to be burned in eternal fire!.