You think "How rude!" She just plain doesn't seem to care. Often, you never hear from her again. If you work with her, or go to school with her, she never apologizes, and if you try to get an explanation out of her, she turns it into your fault.
Roosh explains the flake, and what to do about it.
I Hope She Flakes « Roosh V.
Women do not think or process the world the same way men do. Apparently, if you do the "polite" thing and clear your schedule to spend time with her, she'll see you as lower value and not worth her time. And you'll be left with lots of time to yourself, wondering what to do now because you freed up an evening for her.
I have so many things to do that my schedule is always packed. Every night before I go to bed I fill my next day’s to-do list full of tasks that will keep me busy for the entire day. Dates with girls disturb my work flow and set me back as much as half a day. While I do enjoy dates and want to have sex with girls, I also place great importance in completing my day’s work. What naturally happened was that on the day of dates I began to think, “Man, I hope she flakes so I can get all my work done.”
I noticed something interesting when the thought of “I hope she flakes” pops into my head: the girl never flakes
Yeah, it's not fair. Yeah, they shouldn't do that, but they do. I finally figured out that you can sit around and be frustrated that the world doesn't work the way you "think" it should, or you can study the way the world works and learn to interact with it on its own terms. It's less frustrating that way.