One more thing: this is even worse than Sakura's situation in Chapters 128–129. Fumi is practically always around Shinobu because of their work and the producer's instruction that Shinobu needs to understand Fumi better before filming the sex scene.
It would be completely natural for Shinobu to occasionally stay overnight at Fumi's place, both for discussing the script and preparing for other scenes. Is it really believable that they would never talk about anything before reaching that point?
This is completely different from Sakura's situation, where they were working separately in different places. At this point, it feels like Katsura Airi doesn't care about anything else anymore except forcing an NTR plot into the story.