It is most likely because the title can be read as either Happily Never After or Happily 'n' Ever After (the 'n' being a contraction of and). Along the lines of the former reading, the title could alternately be interpreted to expand to Happily Not Ever After (in treating N' as a contraction of Not). As a bit of linguistic trivia, the word "never" is actually comprised of morpheme "ne" (meaning "not") and word "ever", likewise with: "neither" and "ne" "either"; "nor" and "no" "or". So, the lack of difference between "never" and "not ever" king of goes without saying.