Is It Possible For Really Good Platonic Friends to End Up Together?

Yeah of course. In fact this is one of the best ways to get into a relationship! Think about it; you guys already know each other inside out practically, you know what makes each other tick, what kind of music and movies each other likes, etc etc. Point is, are you willing to risk losing her as a friend completely? If the answer is no, don't get in a relationship with her. Once you get in a relationship with someone it is very hard to go back to being good friends afterwards. Of course, it depends how the relationship goes and if you part on good terms. It is up to you of course but my advice would be if you like her that much, sit her down and tell her and you'll probably find she'll say she likes you as much as you like her. Oh, but please let your girlfriend down gently first ! Hope I hoped! xx