Shared Calendar Events being Deleted

My wife and I share several of each other's calendars. She will receive notifications (several at a time) at 2-3 month intervals, indicating that I am deleting calendar events from her shared personal calendars. I see that these can be restored, but it still keeps happening. Is there a setting to change that will prevent this?

Note - it's not all events, and it's not apparent how far back this is occurring.