Elsewhere, I am sorry this happened to you. I don't think you should take it personally.
Let me tell you a story.
A friend of mine invited a girl to senior prom. Before he left the house to go pick her up, she called and gave some excuse like "we're still eating dinner" or something and told him to pick her up about an hour later.
So, he gets to the house. He meets mom and dad. Girl is still upstairs in her room getting ready. He waits. And he waits.
Finally, mom goes up to check on her. About twenty-thirty minutes later, mom comes down and announces girl is having trouble getting her hair just right. But she will be down right away.
Still he waits. How much entertainment can you have sitting there being scrutinized by mom and pop? He said pop was very friendly and nonchalant about the whole thing. He didn't seem to be disconcerted or care; but mother seemed a little anxious about her daughter.
Finally mother goes up and practically has to drag daughter down the stairs.
It is almost ten o'clock before they leave her house.
By the time they got to the prom, they only had less than an hour and people were already leaving.
I never heard much about this person again till years later when she came up in a conversation. Someone who knew her better, said she had some kind of phobia and could not leave the house.
She was always talking to people on phone and telling them she would come with them, etc. like this girl did to you....and she would never show up either. She didn't really make excuses for her behavior or give any phony dramatic reasons. She was kind of like your girl...just a promise to make it up or something like that.
I also heard that when her family tried to get her to go to some family function, a wedding or something, they had to drag her to the car and she squatted down on the floorboard and would not look out the windows during the entire trip. She was nervous and crying about the trip the whole time. At least this is the story that was reported to me.
I know there must be a name for a condition like this, but I don't know what it is.
I just know if this girl starts putting you through mental gymnastics right off the bat...it's probably best to clear the wreckage off the tracks and wait for the next train.