Was about to say, way to ruin the moment Usami, but these two were already overheating from the moment so I guess it's fine that somebody had to apply the brakes... I mean, imagine if they returned and Kaoruko answered his confession and they all heard. 100% awkward moment for everybody regardless of the answer.
Love how the other three realized something was going on between Rintarou and Kaoruko and were considerate enough not to pry. Usami's just the right kind of dense not to ask inconsiderate questions.
"I can't stand around doing nothing."
"I don't want it to stay this way."
YES. Rintarou is a man of action.