updated 06/22/2012 AT 1:50 PM ET
•originally published 06/22/2012 AT 2:30 PM ET
In her new movie Part of Me, Perry, 27, pulls back the curtain to discuss why her marriage with Brand, 37, fell apart.
The biggest strain on their relationship, she reveals, was her busy touring schedule. As scenes in the movie show, Perry used days off from her grueling world tour to take side trips to see Brand. Yet the time apart still took its toll.