I need help with this girl problem.....?

kay soooo

this girl knows i like her but at the moment she is interested in someone else,

and she is notorious for liking guys she cant have.

anddd basically one of her best friends who im good friends with told me that she kinda likes me but she wants a challenge. and since i already told her i liked her i wasn't a challenge

so i need something to say to like to make me seem like a "challenge" to her

something like

"i was wasting my time trying to be with you when clearly we woldnt work out and besides there are other girls who i had to let down since i wanted you soooo ima just go with some of them"

def not in those words of corse

but somthing along those lines

nothing mean that would make her feel bad

or

nothing that wold make me sound like im completely stuck on myself.

thanks :)