This is so adorable and the exact thing has happened to me a couple of times throughout life (I'm 27 and bi) but I always thought "if we can just be friends, that would be enough!" However when you get closer and closer to them, it REALLY hurts when they get a boyfriend, and even the nicest person struggles to cope. However the good news (for us) is that not a single one of those couples lasted at that age, and they have all gone through multiple partners since - so maybe a friendship is actually stronger, in some cases?

I'd say strive to be friends with her, even if you are awkward and shy (I sure as hell was) sometimes that makes you stand out and they actually like you more for it. However, remember you are young. Any relationships stronger than friendships at your age are unlikely to last. So keep it as friends and try not to let any of her romantic relationships bother or upset you too much.

You could become a very meaningful person in her life, even if not a romantic partner. A lot of people your age however are not fully accepting about same-sex relationships, so maybe don't bring it up just yet, enjoy your time with this girl, make a positive impact on her life by being a good person, and who knows what could happen in the distant future?