Hi lilodian, I'd stand by shezbut's reasons as being entirely possible but I'll just throw in some more maybe's:
She might have been considering starting something......the dating/relationship thing but decided she didn't really want that, or wasn't ready for it at the time regardless of how well it went with you,
She might have just been looking for "a distraction" from whatever,
She might have been seeing someone else as well at the time,
The physical chemistry might have been more that she felt comfortable with you,
She might be the kind of person who just doesn't want to be "tied down" or finds it hard to commit to things (or people),
It might be she decided that you both had too much in common- for some people they do look for partners who are different from themselves.
Still, lots of possible reasons...........and they don't all have to be about anything you or she did wrong. Just don't let it put you off trying though, sometimes you're going to have to go through plenty of people, and plenty of "great dates" to find someone really right for you.
Just hang in there and good on you for "putting yourself out there"!! You know the old saying "If you're not in the game............" or something like that
Alison