I fall very deeply with a girl who likes me but love another guy.. what should i do??

I love a gal very much.. and i want to be with her.. i really do.. the story start when her last birthday.. i said i like her.. and soon i noticed tat i fell in love wif her.. very deeply.. always think of her.. we went out a few times.. i thought she would like me too.. and she did like me.. so i was quite happy.. but i knoe tat she loves a guy before.. she said she will nv fell in love wif this guy anymore.. but this guy finds her when he goes out.. saying he miss her.. i let her sms him.. because i trust her.. until the last day i went out wif her.. she call me to give her up.. i said i couldn't.. and we quarrel until she told me tat.. the guy tat she loves before got a new gal.. and she was so sad.. i say she is cheating herself.. she know.. but because of personal problems can't be wif him.. i said.. u cheated me.. u didn't like me.. but u said u did.. in the end she end wif.. dun talk wif me anymore.. but i still talk wif her.. she cried for him.. still want him back to her side.