The source went on to reveal that there was trouble in paradise for many years and the reboot of the hit reality-TV show, The Hills: New Beginnings didn’t help.
The source added: “It got so bad that Kaitlynn had actually moved out before they started filming, but then moved back in. Doing The Hills magnified a lot of things in their marriage. And it became clear that it wasn’t going to work. They both knew it.”
Another person who supposedly "knew it" was controversial The Hills co-star Spencer Pratt.
“I’m not surprised,” Pratt said on his episode of the Make Speidi Famous Again podcast. “I think season 2 we’re going to get to see real Brody… I think he’s [going to have] way more fun. He’s way less intense. I feel like he has a lot going on, so I just hope we get to see relaxed Brody, having fun, barbecue, for real Brody.”
He continued, “So that I look forward to. I think there’ll be a lot of success in Brody. I feel like I said it that he almost was like a hostage, it felt like he was trying to tell me, ‘Get me out, get me out.’ ”
Montag, 32, continued to admit on their podcast that she “didn’t really” see their split coming, however finding it “fascinating” that the couple had commented on her marriage and Pratt's marriage amid the breakdown of their own.
“It’s fascinating that I felt like they tried to say digs at us about marriage and certain things on the show, and it’s like, we’ve been together for almost 13 years. We have been through multiple reality TV shows, and you’re being weird about us?” she said.
Montag also made it quite clear that she believes Jenner and Carter's problems came from the fact that Jenner openly admitted he was in an open relationship on the show. Apparently, Carter wanted to keep that information private.
“Reality TV is hard and I don’t wish bad on any relationship,” Montag continued. “I think all relationships are hard and you always want the best and sometimes the best is not being with that person. So for them, If that’s what’s best for them, then I think that I fully support that and I hope they both find true happiness and love or whatever they’re looking for.”
Adding to the drama, another source told People that Carter's strong desire to have children was another reason why the pair decided to split.
Jenner proposed in 2016, three years after they met, getting married at the Nihi Sumba resort off the coast of Indonesia in June 2018.
WATCH: Kristen Cavallari chats about controversial The Hills reboot