There's nothing wrong not feeling attracted to her, so you should not feel shallow for it - everyone has different tastes. It is important to be with someone you feel attracted to. However I do not think you should say it to her, it would sound rude and there's not much she can do about it (at least in short term, and according to what you said, she doesn't seem to be willing to change much and is fine with it).
So just come up with some excuse and walk away. Say an ex girlfriend is hitting on you again, and you still have some unresolved feelings for her. This always works for me. Always.









