On the contrary, the Catholic Church holds that a sacramentally valid marriage is indissoluble. This does not mean that a validly married couple cannot get a civil divorce (civil divorce in itself has nothing whatever to do with a sacrament); but it does mean that, even if a civil divorce is obtained, the validly married husband and wife are still married in the eyes of God, and cannot remarry until the other partner dies.
Annulment is a different matter: it is not divorce. It is based on an investigation of the validity of the sacrament and the vows. If both the husband and the wife made sincere vows (they weren't drunk, crazy, immature, coerced, mentally handicapped, ignorant of the meaning and obligations of the married state, etc.) and were truly free to marry (there was no question of incest, bigamy, etc.), the bond stands; but if the vow was null (defective) from the git-go, there was no indissoluble bond. Hence annulment: a finding of no marriage.
I would be truly grateful to be corrected on this subject, but my understanding is that the Orthodox Church under some circumstances permits divorce and remarriage, even if the couple was validly married in the beginning. That's what my divorced/remarried Orthodox friends tell me.
Please direct me to some link if I'm wrong about this. I'm here to learn.
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... )