TEEN STORY, HOW SHOULD I END IT?? PLEASE HELP!?

I like Ash's suggestion. I would invent a third boy, maybe a friend that one of the boys hangs out with, or a friend of your hero's sister, brother, or a neighbor. Don't write a lot about him. Just insert him into the story here and there, and then when you get to the end, she won't have to choose between these two, but takes lucky number three :)