'Divergent' author Veronica Roth has "made peace" with how the movie franchise ended.

After the first two movies were released, 'Divergent' in 2014 and 'Insurgent in 2014, the third book in Roth's trilogy 'Allegiant' was set to be split into two movies.

However, the second movie was never made after 'Allegiant' - starring Shailene Woodley and Theo James - failed to find success at the box office, but Roth insisted she has come to terms with how things worked out.

Speaking to PEOPLE, she said: "I just feel like it's got to be a big, long book in order for that to make sense. I mean, breaking things in two was all the rage at the time. That was why that decision was made. But at that point, I think I always felt peace about it just because I knew the movies were taking a different track than the books, and if you change the lead up, you change the ending. So I kind of felt like at that point ... I feel like that third movie, I don't know — there's a lot we could talk about with it. But it's its own thing.

"It feels complete to me, relatively speaking, because what does that even mean at that point?"

After the book 'Allegiant' was released in 2013, Roth got death threats for killing off the main character Tris.

She said: "I listened to the series again on audiobook recently, and this was the first time I had re-experienced any of the books pretty much since 'Allegiant' came out, because for a while it just reminded me of the internet, intense stress. I'm obviously a lot older, and I think reading 'Allegiant' again I understand better why there was such a strong reaction to this, just because of having that time and perspective. It's interesting to reflect."