Is it always about you??

I always try to give people the benefit of the doubt. Maybe you should approach her and try to talk to her about what was going on during lunch. It does sound a little odd that she wasn't being social, especially if that isn't like her. But maybe she felt awkward for some reason with the other friend being there that she didn't want to open up about why she wasn't being social. Something could have happened if she had just come from work. That can happen at my office as well - I could be having the best day, but then the next minute something happens and completely ruins it, changing my whole mood instantly. The best thing to do it to just talk to her and be a friend. Don't jump to any conclusions and try not to be mad at her until you know the whole story. Then if you still don't get anything out of her, at least you can say you tried. Maybe give her some space and maybe she'll come around at a later time and try to explain what was going on. Good luck with your friend!

i think she just dont know what to say.

There could be a few explanations for your friends anti-social behavior. -You friend could have had something bad happen very near the lunch, and just not been in a very good but but didn't have enough time to cancel. -I don't know how well your friends know each other, but maybe she got nervous around the other friend? -It's also possible she didn't realize she was doing it. I've had longish car rides where I didn't say a thing, but didn't realize it was so quiet until right near the end. -Maybe she also wasn't feeling up to it, but didn't want to risk hurting your feelings by canceling. No matter what the reason, I do agree that if someone isn't going to have a good time I would rather have them cancel than act like a wet blanket and bring everyone's mood down. I understand that sometimes people don;t want to be social, and would rather make new plans to see them when they are in the mood for being around people. That makes it more enjoyable for everyone.