I have to agree with Draconis.
Answer to the next question-- You can only change you , you cannot change her, she has to want to do that herself. It doesn't matter what age you are, passion ebbs and flows. I still get butterflies in my stomach once in a while
As for being so young, you have your whole life in front of you. If it is not meant to be, then let her go and find a woman who wants to be with you. My first husband died when I was 28. I thought my world ended. My life actually just began---heartbreaks hurt but if she is not willing to try and make things right, then you'll experience more heartache later. I hope I wasn't too harsh in my reply.