A non-Christian, if he thought he would not be punished would do it. The Lord is not recommending removing the members of your body, but putting God first. A old testament rule. This is not God's perfect plan, but He allowed it. However, Christians should not get divorced.
Marriage is a spiritual commitment which last for as long as the two live.
Relationship between wife and husband can reach hate over time. If they do not forgive and love then the person can not be a Christian. Christians must forgive each other. He must meet his commitments. Love enemies is the New Testament principle to replace the old.