Suppose the boy ends up with a third girl? The two best friends could then find that their friendship is more important than any boy.
Flip a coin, and make it work. The magic of the writing will take over. I like it when the guy falls for the girls mutual enemy, or one of their sisters.
Oh. That's good, thank you!
I can see why that'd be so hard to write, because either way wouldn't be the best ending. Maybe she could choose the crush, but she would accidentally find out from some gossipy girl that it was the friend who set them up, the friend who really loves her. That way you could find out what the crush would say, but she could end up with the best friend. Or you could take an alternative route, and throw a third boy into the mix, so she wonn't have to choose either. Keep in mind though, that it might get confusing with so many people. If you do bring in a third boy, make sure you characterize him well, so it won't seem like he was just thrown in there so she wouldn't have to make the decision. Go back into your story and add the third boy, if you want him to be a part of it, so it doesn't seem like you just thought of him toward the end. Or, you could add a twist, and maybe the crush could admit he really likes the girl's best female friend, not the girl, so the girl would get the best friend, and the best female friend would get the crush. It may take awhile, but try writing out a few alternative endings, and showing them to your friends, or family members and asking them which they find is more interesting. Good luck, and let us know what you decide!