The Bible says, "God hates divorce" and for the most part I guess we all do. When God made a covenant with Abraham, He made the vow one sided. He made the vow as something He was going to do through Abraham. He would bless the nations through Abraham as the stars in the skies, and bless a people called out for Himself as numerous as the sand upon the seashore. It was a covenant He kept and fulfilled Himself. However, unlike God's covenant, marriage is a two way covenant.
When two get married, it is a covenant between two people - to cherish each other and to love, honor, and obey; through sickness, and in health; till death do us part. The words spoken by the two parties should be as important in their situation as the Words spoken by God to Abraham. When we make a vow about anything, it is not to be taken lightly. Jesus said of the words we speak: "We shall give an account of every idle word we speak on the day of judgment." Our words, our vows, bear the same weight as the covenant God made to Abraham. God expects us to keep our word as He keeps His. Not to be used as an easy way out of a situation, but with deep meaning and commitment. Certainly there are situations which cannot be reconciled and God understands that and that is also why marriage goes much deeper than we consider. Marriage is not a short term answer to a problem, but a life-time pledge to be faithful to the end.
So what is the secret to marriage? It is not of ourselves. It is a vow, a long-term commitment, not only to our spouse, but also to God. God must be and/or must become the center of the marriage for a marriage to succeed. With man it may be impossible, but with God, all things are possible.