1)If spouse of a citizen of India or a person of Indian origin is applying for PIO card, an undertaking from both will be required stating that in case if separation/ divorce the PIO card will be surrendered for cancellation

2);In the event of divorce, the foreign spouse holding PIO card is required to notify the authorities and the authorities would take steps to cancel the PIO card.This does not mean that on loosing the PIO card the person would be instantly required to sell their property or immediately leave iindia

3) the best course for a spouse under such circumstances would probably be to approach the appropriate authorities and try to legalize their stay in India by applying for a different type of visa.

apply for visa to stay in india . foreigners can also apply for Indian citizenship once they meet the residence requirements

By Naturalisation (section 6):Citizenship of India by naturalization can be acquired by a foreigner (not being an illegal migrant) who is ordinarily resident in India for twelve years (throughout the period of twelve months immediately preceding the date of application and for eleven years in the aggregate in the fourteen years preceding the twelve months) and fulfils other qualifications as specified in third schedule to the act, 1955