What should I do? (help:/)?

I really like this boy, and he says he likes me to. but the thing is, he has a gf. he said he wants to break up with her but he doesnt want to hurt her feelings. (she is always saying she wants to marry him and she will never hurt him and things likes.) but me an him are about to be sophomores and she just graduated and is going to the army. i told him to just break up with her but he told me it wasnt as easy as i thought. but i broke up with my bf for him! so obviously it aint to f'n hard! me and him have been in this situation for months. we have been doing stuff behind her back, but i am tired of having to sneak around to do stuff with him. cause i really like him! so how can i convince him to break up with herr? or am i just wastin my time. i told him we have to quit doing stuff till they break up.. but do you think since he is willing to cheat on her with me, he would be willing to cheat on me with someone elsee? ughh, i have never liked someone like i like him! but i really dont want to get hurt. i have been hurt to many times already. and i am sick and tired of playin games with people. so thanks loves, 10 points for the best answer. :)