Our marriage easily becomes our idol, the thing we seek more than we seek God. It is even easier for our expectations of our spouse to become an idol, the image in our head of what our spouse should look like or do.
A covenant is more than a contract. It does not protect our interests, as a contract does. It surrenders them. You come here to surrender yourself to the interests of each other, and you do this by making an oath. There is no mingling of blood, but a mingling of purpose as God himself makes you one flesh.
The covenant you make is sacred and permanent. It is approached with reverence and sealed with blood. There is no backing out or giving up. You will swear before these witness to cherish each other until our Lord comes or until death alone shall part you.