There are certainly ambiguities of translation between Japanese and English (there always are between any two languages), but for the most part, these kinds of ghostings are just straightforward and stupid: "I feel bad and cannot make our appointment today."

There's no subtlety of language; you're just expected to know that this means goodbye forever. To the extent that subtle bat-signals were sent, it was probably when you made the date/appointment/whatever, and missed the uncomfortable body language of the counterparty. That can be pretty nuanced. I'm by no means an expert at this, but I've spent enough time there that I routinely see tourists, newbies, etc., completely missing the obvious social cues swirling around a room.

If I had to guess, the author is probably bad at this and doesn't know it. The stuff about discussing her miscarriage with students, in particular, makes me think she's misreading the level of social familiarity.