Is it the same as the Petrine Privilege? I still do not understand either one.
Catholics who marry outside this form have not contracted a valid marriage.
Okay, so siunevada's friend is not in a valid marriage because the husband was Catholic. Why then is the marriage of two non-Catholics married outside the Church considered valid?
Should siunevada's friend get a legal divorce?
The Pauline Privilege is a historical elaboration of 1 Corinthians 7:10-16, where Paul states that, in the case of the marriage of two unbaptized, one of whom later becomes a Christian without the consent of the other, the convert is no longer bound to remain with the non-Christian. It was used frequently during the missionary expansion of the Church from the 16th to 19th centuries.
The Petrine Privilege is also known as the "privilege of the Faith." It is not found in Canon Law, but developed as a pastoral practice in the US after the promulgation of the first Code of Canon Law in 1917. the Petrine Privilege allows the Pope to dissolve a marriage between a Christian and a non-Christian which by the very nature of the bond, was not sacrament in the first place. There has to be good reason for such papal action: One of the parties to the first marriage (presumably severed in divorce) wishes to marry a Catholic in a second ceremony, or the non-Christian party wants to become a Catholic and remarry.
They are similiar, but the Petrine Privilege involves a marriage between a Christian and a non-Christian, whereas the Pauline Privilege involves two non-Christians, one of whom becomes a Catholic. Both apply to prima facie non-Christian marriages.
Okay, so siunevada's friend is not in a valid marriage because the husband was Catholic. Why then is the marriage of two non-Catholics married outside the Church considered valid.
The Church assumes they are valid, unless proven otherwise (the reason for the annulment process), just as the Church assumes the validity of baptisms in other Christian denominations who use proper form and matter.
Should siunevada's friend get a legal divorce?
That is a matter between those two people, and no one should suggest otherwise, unless one wants to be sued for alienation of affection.