Here’s a wonderful and thought-provoking excerpt from Miroslav Volf’s reflections in Against the Tide: love in a time of petty dreams and persisting enmities.
On love and marriage
Many modern forms of marriage are like contracts – indeed pre-nuptial agreements are legal contracts. A contract can be broken “to pursue new relationships if better returns seem likely.”
A good marriage is not a contract, but a covenant. Covenants are unconditional: we are obliged to keep them even if the partners break the terms. Contracts are temporary: we are bound by them only as long as it suits us (provided we pay the consequences of breaking them). Covenants are durable: we are bound by the marriage covenant “until death do us part.” Contracts are governed by the pursuit of one’s interests. Covenants are governed by the demands of love.
Covenant love is different …
To give less than you expect to receive is selfishness, no matter how warm your heart feels in the other’s presence. To give as much as you receive is to be fair. But to love is to give more than you hope to receive. Is love a raw deal? From the point of view of contractual relations it is. But love has its own rewards. Remember that Jesus said it is more blessed to give than to receive. The return I get when I practice self-giving love is not more to me, but more to us – more to the beauty of our common love.
FaithinIreland 
Wonderful descriptio. And as Christians it is a wonderful thought to realize that God hasn’t called us to a contract but to a covenant with Him and so many times we live as contract people rather than covenant people.