"Even though God did not aim, in the beginning, for marriages to be miserable, many are. That's what sin does. It makes us treat each other badly. Christ suffered and died to change that. … This kind of love is possible because Christ died for both husband and wife. Their sins are forgiven. Neither needs to make the other suffer for sins. Christ has borne that suffering. Now as two sinful and forgiven people we can return good for evil."
— John Piper
Source: Fifty Reasons Why Jesus Came to Die (2006), ch. 35, "To Give Marriage Its Deepest Meaning"