Seeing Kisha clarify her motives to ensure he didn't misunderstand, Duke nodded and happily let go of his earlier sourness. Her explanation showed that she valued Duke's feelings above all else and didn't want to hurt him.
This was all he needed. It didn't need to be spoken; it was enough evidence for him to realize that his and Kisha's hearts were aligned. Duke's eyes formed crescents as he gazed directly into Kisha's.
Those monitoring them from the hidden camera couldn't bear to watch because Kisha and Duke appeared intimidatingly affectionate toward each other, making them feel uncomfortable as if their eyes were under assault.