"After years away, lonely Darren Ashcroft returns to his tiny home village to win back his childhood sweetheart only to be told she never existed."

Wow, I like it! But I agree with what StellaAurora says

To me, it seems like the inciting incident should be that he is told that his childhood sweetheart never existed. So what happens after? And what is the main characters goal? What must he do to reach that goal? (maybe he wants to prove them wrong, to prove that she really did exist and to find out where she is and why everyone is lying about her existens?)
Or, if the finding-out-sweeheart-never-existed part is the twist in the end, what is the story about? What happens before he finds out? And what makes him go back after all these years?

I like the concept and I hope this helped you in the development of the story. :)

Steven: "Too many films have already been made about the guy or gal who returns back to his home town to win back his/her old sweetheart. The first 80% of this sentence is boringly familiar. At a minimum the logline should have read ?Darren returns home to find Sarah. But she - his childhood sweetheart - no longer exists. Everyone denies she ever existed.? THAT much is intriguing!"