divorce

What he was doing for 12 years? What he did for his son for the last 12 years? Even if she was not coming back why he didn't move court for restitution of conjugal rights? All of a sudden after 12 years he's thinking of settle down and till now he was hanging outside marriage with other women? Issue of divorce is not easy at all without payment of huge amount of permanent alimony and for any settlement that sacrifice he has to give.

If both spouses wish they can join and spend their married life together.

The married spouses can seek divorce per provisions of personal law that applies e.g; Hindu, Muslims…

The courts examine grounds for divorce pleaded by spouse that has approached court for decree of divorce…..Both can contest in court and convince the court on grounds e.g; desertion, irretrievable breakdown of marriage etc etc

MCD is the quickest and easiest recourse…For MCD spouses have to settle the terms amongst themselves..on their own or thru elders, well wishers, counselors, Lawyers..The demand may come down..

Work out the options that are most suitable....

Though the disapperance for 12 years is mysterious and has to be explained properly, your friend can file a contested Petition for Divorce.  However, it is possible that the disapperance may do his case more harm than good and his case may be dismissed if his wife contests it properly