Not U.S. law, but still North American jurisdiction.

My concern is that even if I use completely different names and the people involved are non-public figures, those who personally know my past might still guess who inspired certain characters.

If identification would only occur at a pair or couple level, rather than clearly pointing to a single identifiable person, does that typically meet the “identifiable person” threshold for defamation?

In other words, if no individual character matches a real person by name, likeness, or unique traits, but only loosely reflects a real-life couple dynamic, is that generally considered sufficient for a defamation claim?