The Hills star Spencer Pratt claims Kaitlynn Carter was dating Miley Cyrus before Brody Jenner split

Kaitlynn Carter's co-star on The Hills: New Beginnings has questioned the timeline of her romance with new girlfriend Miley Cyrus.

Spencer Pratt claims that the women began fooling around way before they were snapped kissing just one day after Cyrus announced her separation to Liam Hemsworth on August 12.

According to Pratt, Carter and Cyrus were already "a thing" when The Hills reboot began filming late last year, while Carter was still married to co-star Brody Jenner. The couple — who Pratt claimed had an "open marriage" — announced their split on August 2 after just one year of marriage.

"It's tough for me to listen to Kaitlynn complain about people talking about her allegedly open relationship with Brody when we know she had a thing going with Miley," he told Cosmopolitan. "She already had something going on with her when these scenes were filming — maybe not physically, but definitely emotionally.

"No one's judging you for whatever it is you and Brody do when he's not sleeping in his car," continued Pratt, referring to the time Carter made Jenner sleep in his car after coming home at 2am in the morning. "We just don't want people to lie about their lives."

In this week's episode of The Hills, Carter opened up about her marriage to Jenner, saying that she wished her castmates exercised a little "common decency" by not gossiping about her marriage to Jenner. However, Pratt said that her plea comes a little too late, given it was Jenner who had been broadcasting the intimate details of their marriage on his podcast, The Brody Jenner & Dr. Mike Dow Podcast.

"Maybe you shouldn't have gone on television. It's called a reality show, hon. And the reality is that Brody's been talking about your sex life on his podcast for years," Pratt pointed out in Cosmo.

"I would love to know Liam Hemsworth's thoughts on Kaitlynn's recent display of 'common decency,'" he quipped. "You know what I call 'common decency?' Getting it on at your Italian villa and not in front of the paparazzi."