is divorce required for NRI if marriage not registered

I got married in India 7 years ago. Due to shortage of time, unknowingly my marriage was not registered. So, I don't have a marriage certificate. We are Australian Citizens now and according to Australian Law, because we dont have our marriage registered neither in India nor in Australia, we would not be considered as a married couple so we cant apply for a Divorce if we want to get separated. To avoid future complications both in India and Australia, is it mandatory to take a Divorce? Can we marry other people in future? Where would our case stand according to Indian Law?