In reality, rntr and regular ntr can definitely coexist within the same story if the focus is placed on the right emotional and psychological consequences. It is not about removing guilt or turning it into a simple partner swap, what matters is how the characters experience betrayal and loss. The essence of ntr lies in the emotional pain, jealousy, and sense of being replaced, not just the physical act.
Yes, men and women may react to cheating differently, but that does not negate the impact of rntr. A woman who loses the person she has feelings for can still experience deep pain. It is not just about the change of partners, it is about the emotional blow to the character on the receiving end of ntr.
RNTR is not "femdom in disguise," but rather a tool for dramatizing relationships that highlights emotions and the dynamics of relationships. Even if the man stays "faithful" to one woman, the loss of intimacy and sense of exclusivity for another heroine creates the same emotional effects as classic ntr.
For example, there are great games where ntr and reverse ntr are combined really well, such as "Oyako Rankan" and "Mirage's Defection".
As for "the plot demanded it" honestly, you can say that about literally everything in the game, from character lines to their actions. If we go down that road, the discussion ends with "this game should not exist because Asuna would never act like that." But this is a parody, and parodies come with their own nuances.
Regarding Asuna’s feelings, there were clear moments of jealousy toward other girls, both before and after she saw Kirito with Leafa. She is a hypocrite, because despite cheating herself, she still wants Kirito to belong to her, at least for now.