Good question. In life there are choices, and your now-ex has made a choice that you don’t like. Because you’re 18 and she’s 17 (thanks for the pre-posting questionnaire information), she’s probably more in tune with her peers, as a teenager, than she may be later in life when she has more experiences and more opportunities to understand that friends are important, but not at the expense of their being selfish. The cost to her for focusing on her girl code is that she’s losing out on a great guy (that would be you!). Don’t be surprised if she figures this out down the line and isn’t quite sure how to get your attention again. In fact, if you back off and live your life, you may find that she starts flirting with you again to try and get your interest back, realizing her mistake.
So, give this time and space — and be open to her figuring out that what she decided wasn’t the best decision she could have made, or even the last decision on this issue she may make. And if it was…. then she’s not the one for you. 😉