Any successful marriage is built upon the biblical truth that God designed each of us with five purposes in mind: worship, fellowship, discipleship, ministry, and missions.
I have set an example for you, so that you will do just what I have done for you. John 13:15 (TEV)
You and your spouse were both created to become like Christ. God uses your spouse to build his values, attitudes, morals, and character within you. God uses your spouse, and your relationship with each other, to form you into an image of Jesus.
Once you understand this, a lot of what happens within your marriage will begin to make more sense. When you start to ask, "Why is this happening to me?" The answer is -- to make you more like Jesus!
If God's purpose for each of our lives is to make us look more like Jesus, what better tool could he use than the marriage relationship? Who better for God to use to chisel you than the person you live with seven days a week? God is using each of you to shape the other person more and more into the image of Jesus.
God's work within your marriage is designed to produce "love, joy, peace, patience, kindness, goodness, faithfulness, humility, and self-control" within you and your spouse. (Galatians 5:22-23, TEV)