Technically yes, you are supposed to have a return ticket. I would suggest you get in touch with the french embassy to inquiry about your special situation.
Citizens holding passports with other countries should check with the French Consulate. Entry Requirements for French Polynesia Nationals of the USA and Canada are allowed to stay one month without a visa. You must have a valid U.S. Passport VALID FOR SIX MONTHS FROM TRAVEL DATE and a return OR CONTINUING ticket.