She's so flustered she's bolting away before he can say anything and running into telephone poles. She's really struggling to keep it together around him.
Also his friends being pretty blunt about him not being as popular as he thinks he is, hahahah...
Yeah, sounds like he's had an inflated opinion of himself from the very beginning, to be honest. But I suppose that gives him the overconfidence to chase after Shia like he does. Which feels more and more plausible a pairing to me as time goes on, here.