It seems to me like the only reasonable interpretation is that she's got a giant blind spot when it comes to applying that idea to her - something like the whole "sure, but no one would even think of liking me like that, so obviously they were just joking/teasing/whatever". She's got exactly the kind of self-image problems that would make that kind of blind spot reasonably realistic, and she really hasn't had enough friends or even close associates to build any more realistic assessment of her likeability.
That said, she's not really been consistent enough in that for me to feel like it's a really good explanation - she did seem to be expecting (nay, anticipating) that kiss, and she's definitely been shown to be aware of things like her heart beating faster and so forth. Possibly it's less a matter of just being blind to the idea, and more of choosing to be blind to it . . .
Which would make a decent amount of sense, given her view of herself is complex and fairly nuanced, for all that it's extremely negative most of the time. She seems to see herself as being something like damaged goods, even when she can recognise things about her that might seem to have value - it's like she's got something in the back of her brain going "yeah, that's great and all but you're still no good", and she's not even contemplated the possibility that it might be wrong.
Maybe. I always feel like trying to analyse this kind of thing in great depth is just begging for us to find out in a few chapters that the author just didn't think everything through clearly enough . . .
