For me the difference between Aim cheating and Phun cheating is one of lust vs love. I don’t think Noh as anything to feel bad about now that he knows Aim is not a girl Phun needs to keep care of because they had been intimate. The whole reason they decided to cool it was not just to cool down the lust (which doesn’t work and had the opposite effect because it showed that they love each other as well) but to protect Aim reputation. Noh suggested that sacrifice and then finds out that Aim does not deserve to have Phun nor does Phun need to be loyal to her anymore. This next episode should be telling because we have Aims attempt to seduce Noh and Noh and Phun kissing. I believe both are in the novel so we will see if the producers mess with the novel at this point or not.