1)you are being taken for ride by the girl
2)if you are paying RS 30 lakhs for purchase of flat your name should be reflected in sale deed as co owner .
3) your interests are protected if in the sale deed your name is reflected as co owner
4) however dont make any investments now . you dont know her nature. after marriage she may change her colours
5) you would have to file suit for partition for division of property if you want to sell your share
6) keep your money in mutual funds or other investments in your name only .
7) stay in rented flat after marriage for some time then take the call