A friend of mine. I wish was my girl?

I have had this girl friend of mine for 7 years. Very close friend. I basically am in love with her and she kinda wants to keep the relationship friendly. Is there any certain reason that could be? I mean I am stable I have a career ( Fireman ). I really do like her a lot and when were together we click perfectly. How should I go about getting together with her? Or should I leave it strictly a friendship??