Don't take this up with HR right away. This is a person that is taking advantage of your personal relationship within the work area.

You need to have a talk with her one on one. Explain to her how you feel and why her actions make you frustrated. Tell her it's nothing personal and all business. Explain to her that your intentions are not to make her life difficult but to make things easier for the both of you. Things are better accomplished when everyone works efficiently as a team member.

If she doesn't take you seriously after that, then you only have the option to take it up to HR.