Paul's advice in Colossians: "Bear with each other and forgive whatever grievances you may have against one another. Forgive as the Lord forgave you."

That's the heart.

It assumes a couple of things. First, that you recognize that you have grievances against one another. For every sin I might complain about in someone else, they've got one they could complain about in me. That's not to say that all wrongs are equal to each other -as if to excuse bad behavior. That's to say that none of us has an ivory tower to preach from. If we talk about sin, we're all discussing it down in the pit together.

And second, it presumes that we realize that we've been forgiven ourselves. The Lord forgave us - paid for our sins although we didn't deserve it. Your husband or wife (or friend) doesn't deserve your forgiveness either - but you can give it because you can afford to forgive. You are overflowing with forgiveness yourself, given to you from the Lord.

Even if nothing else about this marriage works the way I think it should, even if everything in life is turned topsy-turvy, if this one thing is right then everything will be fine. Neither sickness nor health nor riches nor poverty nor rain nor sleet nor dark of night will be able to upset the marriage that is filled with Jesus' forgiveness.