Those Not-So-Sweet Boys Vol. 6 (manga)

After his confession at the school festival, Rei and Midori are finally a couple! Things are going well until one day, Midori is scooped up by Rei’s grandmother and forced to attend the Ichijo matriarch’s birthday party. Overwhelmed by the difference between her world and Rei’s, and facing intense pressure, Midori retreats…only to find that Rei is now more distant than ever.