I don’t think the mangaka wants to do that! The Mangaka loves the subtext, something not very obvious that it’ll drastically take the plot in a point of no return but extremely gradually move the romance, unless this is another way to avoid the stigma by the censorship..
I was being facetious, canonically this relationship is as glacially slow as the antarctic ice sheet. And I'm here for it.
In any case a smooch from these two, in canon or in our heads, would need to be most awkward one possible.
It has to be accidental, or it misses the mark, teeth hit, bad breath from all the karaage, etc.
Maybe all of the above.