For Roman Catholics, Holy Matrimony is a binding, ostensibly an unbreakable, contract. The man and the woman marry each other with the "church" (bishop or priest) standing as a witness to it. Hence, no divorce under any conditions - no divorce but annulment of the marriage contract if some canonical defect in it may be found which renders it null and void (as if it never took place).
In Orthodoxy, Holy Matrimony is not a contract; it is the mysterious or mystical union of a man and woman - in imitation of Christ and the Church - in the presence of "the whole People of God" through her bishop or his presbyter. Divorce is likewise forbidden, but, as a concession to human weakness, it is allowed for adultery. Second and third marriages are permitted - not as a legal matter - out of mercy, a further concession to human weakness (e.g., after the death of a spouse). This Sacrament, as all Sacraments or Mysteries, is completed by the Eucharist, as St. Dionysius the Areopagite says.
http://www.orthodoxinfo.com/inquirers/orth_cath_diff.aspx
(Noting the assumptions on the Roman beleif may not be correct... )
Note that in the Catholic Church, as in the Orthodox Church, "marriage is the mysterious or mystical union of a man and woman - in imitation of Christ and the Church -"
It's more than a contract. But in the Catholic Church, it's never less than a contract. The Catholic Church respects people enough to respect their vow: "til death do you part."