I only say that because years ago I had a girl friend, that I only looked at as a friend, but I knew she was developing feelings. Once I sensed that, I had a talk with her and told her that I really valued our friendship, but that it was just that, and if she had to have more we probably shouldn't be so close.
She said oh, no problem, we're just friends, don't think anything else. So all was good for a few days and then I got my mail and she had wrote me a 3 page love letter, which to be honest, was the sweetest, most genuine, heartfelt letter I've ever received. But it basically ended our friendship forever. Kind of unfortunate, but be careful of your feelings :)