Kouhei's not the one thats acting clueless here. Its Kaede who's too blinded by the concept of childhood friends to realize how her behavior comes across
I dunno - there's a
ton of panels of her blushing and looking at him sideways, especially when some of the other sorta- and confirmed-couples are doing Couple Things, and I think you could argue that she's not "blind to her behavior", but being coy, just like you read in tons of romcom manga where things carry that double/implied meaning.
I'm getting the strong impression she's hiding behind the Childhood Friends label but wants it to go further, but wants Kouhei to "confess to her", given that's a pretty standardized trope methodology to romance stories of yore.
Kouhei wants the same thing, but
is currently wrapped up in just assuming Kaede
does want really want to adhere to the "Childhood Friends" label, and thus is not pushing his luck out of respect for her based on that assumption.