A 'CHEATING' SCENARIO SHOULD NOT BE THIS CUTE! (N.B., unsure if that really applies here; the Chief's wife has left him, though no official divorce seems to be in effect). Still, in another work, Oyamada might have used this (a-hem) moment as job security or extortion; instead, she probably restored the Chief's blood pressure down from dangerously high stress-induced levels, as well as probably gave him a much-needed confidence booster that "he's still got it".
What a great security guard, definitely deserves a raise for playing wingman and keeping it on the quiet. I do feel a bit bad for him considering his situation, and she's a nice girl, trying to cheer him up...the hentai way.