Premarital relationship

A boy loves me a lot. He proposed for me and I said that I will tell my mother and afterwards my mother will decide. He told my mother that he loves me and wants to marry me. Now the main problems stands here. I am too young for marriage so is he. He doesn't have any job. He is still studying. After he told my mother, then we started to talk to each other and as time passed we shared a lot of things. It has been nine months now and he loves me since 2011. Now suddenly I realized that this is haram. I know I did wrong but I have realized it. Now the main problem is that I promised him that I wont leave him but I am a Muslim so is he. I just want to stop talking to him. I want him to wait for me till I am old enough and he is capable enough to raise a family and during this time period he keeps no contact with me. This is difficult for me as well as for him, but he doesn't understand. He wants a haram relation and wants to meet me alone and I don't want that. I love him a lot and I don't want to say yes or no. Please help me. What should I do?