Mandy Moore Reveals 'This Is Us' Season 6 Features 'Heartbreaking' Breakup

This Is Us has made a name for itself with heartbreaking twists and turns for the Pearson family, and there will be no let-up during the sixth and final season. One of the major surprises will involve a remaining mystery between Rebecca Pearson (Mandy Moore) and Miguel (Jon Huertas). After Jack (Milo Ventimiglia) died, Rebecca and Miguel married, as viewers have known since the show's first season. However, it was later revealed there was a long gap between Jack's death and Rebecca's second marriage. Why did Miguel and Rebecca go their separate ways before marrying? That will be explained soon.

The scene that will pull the curtain down on the mystery "gutted me," Mandy Moore told Entertainment Weekly in a preview for the final season. "It's so beautiful and so simple," the Emmy nominee continued. "Rebecca and Miguel collectively reach this boiling point where neither of them can ignore that there's sort of this unspoken chemistry. And someone needs to do something about it. And you'll see how that unfolds. But it's heartbreaking and so true to life."

"It's one of the saddest moments that I've felt as a character, as an actor, and even as an audience member and a fan of the show, too," Jon Huertas said of the scene. The moment was "so tough, so sad," but it will help viewers understand that Miguel and Rebecca were really meant to be together. "As weird as it was in Season 1, Episode 2 to see these two together, this moment, I think, will make people go, 'They should be together,'" Huertas said.

At the beginning of the show, Miguel was met with hostility from fans who thought the character just swooped in and married his best friend's wife right after Jack died. However, fans have warmed up to him over time as Miguel connected with the "Big Three" – Randall (Sterling K. Brown), Kate (Chrissy Metz), and Kevin (Justin Hartley). Huertas enjoyed playing a character who was once hated but now loved. "I get tweets or on Instagram, people say that they actually love Miguel, they love who he is to the Pearson family," Huertas told EW. "That's a testament to the writers and their plan, because at the beginning I was like, 'Hey guys... what are we doing? I don't want to be the guy who nobody likes on the show.'"

Rebecca was also diagnosed with early-onset dementia, which, of course, will only bring more heartbreak to the show. Still, Moore assured fans that Season 6 will be gutting in a "beautiful way" for Rebecca. "Gutting in real-life unfolding in the way that it does for all of us. All of the expectations and questions and all of that is going to finally culminate. I think people will be really satisfied with what [series creator Dan Fogelman] has in store for how the show ties up."

This Is Us Season 6 begins on NBC Tuesday, Jan. 4 at 9 p.m. ET. Past episodes of the series are available to stream on Hulu and Peacock.