Yeah, I'd also bet that you didn't get sexual with her. She most likely saw you as a nice guy and bam...no chemistry. Don't get down on yourself about your looks. It's not about what she "think" about you. It's ALL ABOUT how she FEELS about you. She can think you're ugly all she wants but if you have good game she'll FEEL attracted to you. Her friends will ask "What do you see in him?!?" She'll be like, "I dunno...there is just something sexy about him!".
When I phuck up and don't get the girl I do get a bit upset. Not mad or sad, but definitely frustrated. Which I see as a good thing. Cause the feeling of frustation is, in a way, a positive emotion. It just means that deep down you know you can achieve what you're setting out to do but so far have been unsuccessful. I use that knowledge to push me on and meet other girls, learning from past mistakes.
The more you learn and more girls you see the more you realize just HOW MUCH is determined by your personality. Cliche, I know, but true nonetheless.
-Soma