Yes, Inoda fucked Asuna right next to Kirito while he was invisible, but having sex right next to a sleeping Kirito, literally a few centimeters away, is one of the NTR fetishes. There must be such a scene. I thought such a scene would be in their bedroom at the base, but it would have been even better in the Aincrad hut. The scene in which Kirito sleeps and hugs Asuna, and Inoda penetrates her from behind. During the process, Kirito may even wake up, but Asuna will say, "nothing is going on, my love, go back to sleep."
If Asuna sees Kirito fucking someone again, it doesn't make sense anymore. Asuna already thinks that Kirito was in the brothel and that he was cheating on her in the game. "It's just a game," remember? And where can they go next with Inoda? In fact, all that's left to try in the game is cheating right in front of Kirito, while he thinks it's hallucinations, and anal. Everything else has already happened.
Fujino is obviously preparing to add more action in real life. And the scene in Aincrad's cabin, I think, is more needed to break Asuna's love for Kirito. Well, or replace Kirito's image with Inoda's image in order to bring the relationship above 500.