Oof. On one hand, that dense fool. On the other, yeah, that sorta what happens when you're a teen who's insecure trying not to read too much into things with your crush.
But he knew exactly what she was thinking. If he didn't, he wouldn't have suggested going home together. The premise doesn't seem to work in this short story.
@Simkin he's not dense it says in the synopsis that he likes her but can't tell what she's thinking. He's just taking advantage of a situation! Also we can't tell if the girl actually likes him or not. It could be that she said it on whim or it was calculated. Either way it's left you to interpretation.