It's been almost six months since Russell Brand filed for divorce from Katy Perry and the pop star has largely been quiet on why things didn't work out. Until now.

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.

In one scene, Perry is seen sobbing uncontrollably backstage – minutes before show time. Eventually, she rallies. "Start time," she says before hitting the stage.

Perry also hints that her rocketing music career was a source of tension between her and Brand. "I thought to myself, 'When I find that person that's going to be my life partner, I won't ever have to choose [between the partner and my career] … they won't be threatened or have weird motives," Perry says. "Then I started to realize, that's not true. That fairytale I had is not true for me right now."

The pop star says she did everything she could to save her marriage. "I have that same belief system with everything, from career to my life to my personal life, everything. And I will do everything it takes to not fail. And I did everything it took but it still failed."

Paramount's Part of Me opens July 5.

沪江娱乐快讯：离婚半年来，凯蒂·佩里一直不愿多谈这段婚姻失败的原因，这次“水果姐”终于开口了！在她7月即将上映的3D纪录片"Part of Me"中，凯蒂透露自己繁忙的事业是导致两人婚姻失败的重要原因。为了维系婚姻，凯蒂总是会在忙碌的世界巡演中抽出时间看望丈夫，可惜这样聚少离多的日子终究无法长久。“我做了能做的一切，可是最终还是失败了”。

这部展示凯蒂生活的3D巡演纪录片"Katy Perry：Part of Me"将于今年7月5日正式上映，让我们一起期待吧！