There are certain teachings which the Catholic Church does not have the power to change. The law on the indissolubility of marriage is one of these areas: What God has joined together, let no man put asunder (cf Matthew 19:6-9). The Church has consistently upheld this belief for 2000 years. From St John Chrysostom to John Paul II the teaching remains constant.
Annulment is not divorce. Annulment is a decree that no marriage ever truly existed owing to lack of consent, understanding or defect of form.
Catholics who are in an abusive or unhappy relationship are not forbidden from obtaining a divorce, which is a civil procedure. They are committing no sin by getting divorced and should continue to play a full and active role in the Church.
Catholics who have divorced and remarried, however, are in a different position. Since the first marriage remains intact, there can be no valid second union. These people, owing to the fact that their irregular state is continuous (unlike a one-off sin which can be repented and forgiven) and objectively contradicts the teaching of the Church, may not go to Communion.
They are, however, encouraged to come to Mass and participate as fully as their state allows.
Marriage is in crisis. UK figures show that in 1969 there were 51,000 divorces; in 1995 there were nearly 160,000. As things stand almost half of all new marriages will end in divorce. Preparation for marriage is therefore very important.
Details on Arranging a Wedding