You have said it yourself -
Just believe her and keep it moving.
However that is in hindsight. She did not want to be on a date so she unexpectedly brought a friend. The whole situation was awkward and thereafter it went downhill with your comment. This date is full of good lessons to learn - hence it was not a total disaster.
Posted using Neoxian City
You have said it all. She definitely brought her friend on purpose since she wasn't interested. Anyways, I have learnt her lesson.