Paul addresses this issue in a general sense when he says, “bearing with one another and, if one has a complaint against another, forgiving each other; as the Lord has forgiven you, so you also must forgive” (Colossians 3:13, also Ephesians 4:32). When someone says to me, ‘I can’t forgive so-and-so because…’, I ask them to read this verse in its context. Then I ask, ‘what if God said the same to you because of all your sins against Him?’
God’s forgiveness toward us is very humbling and makes us realize that forgiving another imperfect person is far different than a perfect God forgiving a sinful man or woman. Put in that perspective I can understand why Paul put the two situations in contrast to each other. I want to forgive my spouse considering what God has done for me. This requires showing forgiveness in my attitude toward the other person. This springs from the heart, not just mouthing words that are empty. As a child of God, I have the same basis to forgive another person as God had in forgiving me – His Son! This test will show how we are drawing from the grace we have in Christ for our marriage.
“A happy marriage is the union of two good forgivers.” Ruth Graham