I still get the misguided feeling that atm, Yamada is still friendzoning the MC.
Which is quite a nice contrast, imo. MC is definitely still suffering from Chinbinyou syndrome, but he is aware of this while embracing it (which is considerable for his age), and has greater general insight than he gives himself credit for.
Yamada, in contrast, is physically mature - but doesn't seem to be mentally so, from the manga perspective. Who knows though...