I agree with the discovering Suguha doing something to Kirito as the more likely catalyst to make the real world sex between Asuna and Inoda happen. Fixing the relationship between Asuna and her mother would increase her affection for Inoda. However I think the most important thing that needs to end up happening is her affection for Kirito decreasing, and only Suguha raping Kirito at night has the best chance to really accomplish that barring some random series of events that just make Kirito look like an asshole (like the treehouse event).
Cause I agree that it doesn't necessarily have to mean that Inoda finds out it's Suguha that's raping Kirito, and just that there's suspicious noises coming from Kirito's room at night to be enough of a catalyst. The only thing I'm confused about is that for the in-game Monday - Wednesday we're going to focus on real world stuff, and personally I felt that them discovering Kirito with Leafa seemed like the more reliable thing to do in terms of making Asuna believe Kirito is cheating. But yeah, since we're focusing on real world, I'm wondering if Fujino intends to make Asuna and Inoda have sex, which feels unfortunately too soon since none of the big events to make her lose more trust in Kirito didn't happen yet it feels like.