If there's an attraction, and she has a boyfriend, how do you move the relationship on to being friends (long)?

hey not a strange problem.U need not avoid her but just be with her and flirt her as she does to u and enjoy the moments.Only thing u need to do is to praise another girl or point out many girls around that they r beautiful.Make her feel jealous.Don't involve too much in temporary relationships.If u move miles from her from vacation.Just don't call her though she is in ur mind always.Call only when u receive the first call from her.confirm first whether she is in relation with a boy and ask her to introduce to him.If she is in serious relationship live with her memories.There r billion nice and beautiful girls on this planet who can hold ur breath.No ideas of how to flirt just browse in google u will find a number of them.Enjoy life,don't waste in infactuations.By the way what is ur AGE???????????????????