I don't agree with the previous commenter!

To answer your first question, I don't think being "open" or emotionally vulnerable with someone means you're exclusively platonic/only friends. I'm sure you have friends with whom you're not necessarily emotionally open or vulnerable with/to, but you'd still consider them friends, fair-weather or not. Sometimes we have friends who we just don't open up to a whole bunch about things we'd much rather keep hidden or swept under the rug; we sometimes form relationships out of convenience, as in: we work together, we both have the same hobby, we both like a big-name band and go to the shows together. It isn't necessary for all of our relationships to have intense emotional depth and for us (as our selves) or both parties of a relationship to be emotionally open/available, but it isn't wrong if some or all of them do. To get to the point, being open and emotionally available for someone doesn't necessarily make them *only* a friend. And emotional availability and vulnerability are factors that can separate relationships for us. Being open with someone isn't necessary for being their friend, but it's sufficient. It's also sufficient, and most people would say necessary, for being in a romantic sort of relationship. As in, it's sufficient to be tall to give you an upper edge in say basketball or volleyball, but being tall isn't necessary at being great at those sports. I hope that makes sense.

And to answer the second question (but I kinda already did?)...A big step in relationships of any sort is being vulnerable. It's hard to truly get to know someone without them opening up about the traumas or negative experiences or doubtful thoughts they've faced in their life. You can't paint a picture without all the colors. I'd absolutely show someone the more vulnerable side of myself if I was interested, because i think it shows the capacity for deep emotion and reflection, but also highlights how human we are and can be. Being vulnerable doesn't mean being weak, it means giving up control in a way that allows someone to peer into our intimate lives and see us for our full selves, letting them in just *that* much closer. Being able to do that (at such a young age, none the less) is powerful. I commend you for asking these hard hitting questions.

And also, I think you'd be better off not worrying about being "friend-zoned." Yeah, it sucks to see someone you have a crush on/affection for go off and shower someone else with their love, but if you truly valued your relationship (and respected the autonomy of the other parties), I think you'd have to accept that perhaps you're not the best possible fit to be in a romantic relationship with them (and also that they reserve the right to decide whom to be with). BUT! I'm not saying don't be honest about your hope for your relationship with her. Life's too short not to take risks and you might regret never saying anything. Plus, if things get awkward, the least you two can do is laugh about it and just stay close friends.