Can I extend the fiancee visa?
No- the fiancee visa is a single entry visa that can neither be extended nor transferred to another category. Your fiancee would have to return home and you would have to file for another petition and wait for the new visa to be approved some months later to allow for a new 90 day period of stay. Keep in mind that a subsequent visa need not be granted unless the consulate feels that a marriage is likely to occur the second time.
