In Aggretsuko Season 3 Episode 8
Haida has both Retsuko over for instrument lessons and then later Inui over for dinner. It is clear that Inui notices the clues that someone else has been here before. Upon finding Retsuko's handkerchief in the bathroom, she then decides to leave.
Why didn't Inui ask about it and instead jump to conclusions?
Haida could have had a female friend (what actually happened) or a female family member who stopped by before she was there, which is completely acceptable.
Was it because
Retsuko and Inui walked past each other when going to / leaving Haida's place? This also still could have been a coincidence. How would Inui even know what Retsuko's handkerchief look like?
Is this a cultural thing? There could have been other explanations.