Did you read Veronica Roth's (theartofnotwriting) awesome Goodreads interview? Initiates asked Veronica about getting into Four’s head, her tips for aspiring writers, and how she feels about the fan response to the ending of ALLEGIANT.
Read the interview here.
(Warning: ALLEGIANT spoilers ahead!)
"It was both an extremely difficult decision and a decision that I made very early on in the series (after finishing the rough draft of DIVERGENT, in fact). Ultimately it was the ending that felt most true to Tris’s character, and I was determined that she should end up exactly where she had chosen to go."