Well, you may be disappointed. I'm not going to point you to an obscure verse you've never thought of before. There's no tricky exegesis or new way to translate a familiar verse. It's simply a matter of applying to marriage the truth about how believers are to live the Christian life.
Colossians 3:12-15 "Put on then, as God's chosen ones, holy and beloved, compassionate hearts, kindness, humility, meekness, and patience, 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. And above all these put on love, which binds everything together in perfect harmony. And let the peace of Christ rule in your hearts, to which you were called in one body. And be thankful." (ESV)
Philippians 2:3-4 "Do nothing from selfish ambition or conceit, but in humility count others more significant than yourselves. Let each of you look not only to his own interests, but also to the interests of others." (ESV)
And the temptation will be to think, "Yes! If he would just live by this truth, our marriage would be better." Or, "If she would just live out these verses, we would be on our way to happiness." But (and in this blog, I'm assuming both husband and wife are believers) resist that urge. Point the passage at yourself and by God's grace live out these truths; repent and seek forgiveness when you fail to do so; forgive your spouse when they fail in these things; and look to God for daily strength, grace, and forgiveness. I guess the secret to a happy marriage isn't so secret after all.