I don't think I'm being unreasonable to be pissed off here, I just wonder how other people would handle this. My friend often cancels things last minute (day of or night before whatever we are doing). So far I've always wanted to say something but have thought what's the point in giving her grief, it's obviously just the way she is, even though I've been pretty inconvenienced by it in that I've had to go to something by myself that I wasn't really comfortable with being alone at or I've turned other things down and then missed out because we had planned something. She has younger kids than me so lack of babysitting is usually the excuse but to be honest sometimes her other excuses are kind of lame and I get the feeling she just can't be bothered that day.
So today she cancelled on me for an event she knew I was looking forward to and knew I didn't want to go to alone, plus I had thought I might invite a few other people but she'd said she really wanted to catch up, etc. so I didn't invite anyone else as back up in case she dropped out. Again, it was a pretty lame excuse and she only told me when I contacted her about what time we were meeting. Now I'm thinking if I just keep saying "oh it's fine, I understand" she'll never realize that this is not a good way to treat people. I'm a bit non-confrontational though. Or I suppose the other option is just don't make plans with her where I'm really relying on her to turn up? I guess people might also say she's not that great a friend so why bother but I don't think I'm ready to just forget the friendship.