H2O Name Problem

[H2O Loner]

Right basically im doing my orientation this sunday and once its done i know that im aloud to change my name so that i have H2O infront of it but this is were my problem is my girlfriend doesnt want me to change my name because its the first name that we met on (i met my real life g/f on xbox) and therefore she doesnt want me to change my name whenever i bring up the subject with her she keeps getting in a huff so to put it and i dont want to hurt her feelings yet i really want to change my name. i would create another account but i havent got enough money to make another one ill only have enough to change my name just about. can anyone help me out on what to do im really stuck!.