How to get my perfect girl back?

I met this girl who liked me when we first met, and then we got to know eachother and i asked her out on her birthday and she said yes but when school starts. i said i was ok with that, later in the past few weeks she told me that she has this other guy that also wants to go out with her. I asked which one she wants to go out with and she couldnt decide. earlier this week she decided it was me and then i thought i had her that night, and so that guy got in a fight with her and so she chose him today. she is the most perfect girl in the whole wide world and i dont want to lose her, please dont be trollin, im really sad right now. anyways, i told her i was sad but i didnt fight with her or anything but i let her know i was a little bit sad. i can tell she still likes me, i want her to choose me and not him, shes not gonna date until the end of august and she keeps going back and forth. i dont want to lose her :(. can someone plz help me on how to get her to choose me and take me back? we are going to go to the rollaway (roller skating place) in 2 days and i want to get her to choose me, she said we could kiss at the rollaway if i wanted to, and she hasnt acrually gone anywhere with that guy yet, and i have been to her birthday and a bunch of other stuff. she is the one for my heart, she is my perfect girl and i dont want to see her go, please no trolls, can someone plzz give me some advice on what to do at the rollaway and what to do to get her to choose me and be with me???