With both girls seeming to agree they're going to try to escalate things, will Tadano even have the choice to leave things as they are? If he goes full density harem protag from here it'd totally ruin the manga.
Mind you, there seems to be money in that dragging things out way past the point of sanity. Is it some Japanese taste thing where they like shit unresolved as long as possible and end series always when the relationship actually starts, right when it'd get most interesting?