I am the Kat that Walks By Itself

It's a Harry Potter thing; it stands for "Epilogue? What Epilogue?". It refers to a story which is canon-compliant through to the last chapter of "Deathly Hallows" but which ignores the Epilogue which takes place 19 years later. It's frequently used in Severus Snape/Hermione Granger stories where the author wants to be canon compliant with the small exceptions that Snape isn't dead (and often that Hermione isn't married to Ron); since both of these things were confirmed in the epilogue, it's simpler just to ignore the epilogue.

So technically, it's just AU, but in a very small and precise way, so it makes sense for there to be separate term for it.

The story we were discussing on Friday night would be classed as EWE.