Bridge...on one level you sound very wise. You clearly know you do not want a romantic relationship with this girl, though it sounds like she has romantic intentions. I think the best recourse is to be open and honest up front. Much hurt can result from miscommunication, and you don't sound like the kind of fella who would mislead a vulnerable girl. If she is offended by your desire for only social friendship, then that is her problem, not yours, as you have not lead her on.
Patty