> if you were talking to me about something, and midway with no warning or other signal

This happens all the time in a social group setting though. Not much confusion ensues.

Not if you're my wife.

Sometimes I spend several minutes of a conversation trying to figure out which thing she's talking about, because we've already covered like twenty different topics in the last ten minutes and she seems to just switch around at random and with no warning.

Sometimes I get enough context that I can make that swap or stack pop, but many times not.

I think wives believe their husbands can read their mind, and they get annoyed when that doesn't happen :)

But yah, this is exactly what I mean - without some cue, neither humans, nor machines, can tell when you switch conversation.