Recently, I began my work on an independent research project. A few months ago, while I was writing the research proposal for submission, I talked with a peer of mine who hadn't done independent research. As a good gesture, I told her that we could work together on it, since it would help her resume. In the meantime, I planned, wrote, and submitted the entire proposal myself.
When I offered her this "opportunity", I hadn't really thought things through. Now, I've realized that there really isn't much that she can contribute to the project besides stick around and do manual data entry - all of which I can do (she studies physics, while this is chemistry research).
I've already began the project and she hasn't done anything yet (because she doesn't really have the skills or experience, and it'd be too difficult and time-consuming for me to teach her). While I could definitely keep her around since she wouldn't bother me, I feel like it'd be unfair because I would be doing everything, but she would also receive the credit for it (and my "contribution" would therefore be viewed as less).
I'm not sure how to tell her that I don't want to work with her anymore in a way that she wouldn't be offended, but also in a way that doesn't make me look too bad for "going against my word". Any suggestions?