A learner contacted a Japanese-language volunteer on the day of a lesson to ask to cancel. A report from Shimane records that the volunteer felt distrust at the time. It later became clear that the learner’s child had suddenly fallen ill.
The episode appears in a 2019 presentation by Shimane Prefecture and the Shimane International Center. It is the support organisation’s account, rather than an interview with either person. The report describes a gap in Japanese communication: the cancellation was communicated on the day, while the reason became known later. MEXT: Shimane’s report, page 12, first example under Case 1
The cancellation came first; the explanation came later
The request and the later explanation concerned the same cancellation, but they provided different information. At first there was a request to cancel; afterward, the child’s illness became known as the reason. How that reason was conveyed, and what happened to the relationship afterward, are not recorded.
What makes this episode useful is the difference between the information available at those two points. The later account adds a circumstance that was missing from the initial picture.

Make the change easy to confirm
If you need to cancel a lesson or appointment, identify the date and time so the recipient can tell which arrangement you mean. Say whether you are cancelling that meeting or asking to move it. A short reason can help if you are comfortable giving one; an explanation need not include private details.
Ask the recipient to confirm the change. If you want another meeting, treat the new time as a separate arrangement that also needs agreement. Sending a message and receiving confirmation are two different steps.
If you receive a cancellation and need more information to rearrange the session, ask what needs clarifying. Where language makes that conversation difficult, ask the organiser what help with communication is available locally.

For a different account of words and perceived intention, see what one Japanese recipient heard in understandable Japanese. For the cancellation you are handling, check which meeting has changed and whether there is a next step to agree on.