It stands for "Epilogue, What Epilogue?"
In addition, the term is mostly used by slash fanfic writers who were upset at the end of the novels that there were no clearly defined homosexual pairings.
Tommy: That should be easy bro check out the E.W.E. on her. It will be like shooting fish in a barrel.
I saw an obvious ewe the other day headed into an Apple Store. Probably on his way to meet up with his Apple sheeple flock.
Stop copying everything I do. You're such a ewe.