Peter Sarsgaard and Maggie Gyllenhaal are, in fact, the real thing.
And after more than 14 years of marriage, the Memory actor chalks up his long-lasting relationship with the actress to one basic rule.
"Tell the truth," Peter told E! News' Francesca Amiker in an exclusive interview. "Isn't that all there is? It's pretty simple. It's not that complicated. Isn't that the secret to any friendship or relationship?"
For Peter—who shares kids Ramona, 17, and Gloria, 11, with Maggie—honesty is, indeed, always the best policy.
"Otherwise, even if it's a nice lie, even if it's a lie to prop someone up or help them avoid what they're trying to avoid, you're not living in reality," he continued. "And that's the only place to live in."
And these days, they're living in—and relishing—the holidays and their annual traditions.
"There's a church that we go to that has a midnight mass that I don't go to any other time throughout the year," the 52-year-old, a close friend of Maggie's brother Jake Gyllenhaal, explained. "The midnight mass there is extraordinary, and Maggie and I are sometimes able to sing."
As for the ultimate present he thinks you can give to someone? Much like his character opposite Jessica Chastain in Memory, it involves allowing another person to simply be themselves.
"Being a mirror, just reflecting what you see accurately," he noted. "That's the greatest gift you can give anyone. A partner, a friend, anything."
Memory hits theaters Dec. 22 in New York and Los Angeles, followed by a nationwide release Jan. 5.
Until then, to see how more of your favorite stars are getting into the holiday spirit, keep reading…
Mariah Carey
The self-proclaimed Queen of Christmas opened presents with her and ex Nick Cannon's 12-year-old daughter Monroe.
Miley Cyrus
Referencing her own song, the pop star quipped on Instagram, "It’s definitely a Nashville party."
Gabrielle Union & Dwyane Wade
The couple brought on the cheer through festive PJs, rocking them with kids Kaavia, 5, and Zaya, 16, on Christmas morning.
Vanessa Hudgens
You can bet on it that the High School Musical star's celebrations included her beloved dog Darla.
Kaley Cuoco & Tom Pelphrey
The Big Bang Theory alum and the Ozark actor celebrated their first Christmas as parents with 8-month-old daghter Matilda.
Tamar Braxton
Two months after their breakup, the "All the Way Home" artist and her Queens Court suitor Jeremy "JR" Robinson got engaged again on Christmas morning.
Brian Austin Green & Sharna Burgess
The kids are all here! The Beverly Hills, 90210 alum is joined by his and Vanessa Marcil's 21-year-old son Kassius—as well as his and Megan Fox's kids Noah, 11, Bodhi, 9, and Journey, 7—for a family photo with the Dancing With the Stars pro and their 17-month-old son Zane.
Alicia Silverstone
"Just an elf on your shelf," the Clueless star wrote on Instagram. "Happy holidays!"
Billy Ray Cyrus & Firerose
No achy breaky hearts here as the singers celebrate their first Christmas as a married couple.
Courteney Cox
The Friends alum joked that she's on "good terms" with Santa.
Kelsea Ballerini & Chase Stokes
As the country singer wrote on Instagram, "merry chrysler."
Simone Biles & Jonathan Owens
We're flipping out over the gymnast and football player's first Christmas as a married couple.
Derek Hough & Hayley Erbert
Two weeks after she underwent emergency surgery, Hayley and the Dancing with the Stars judge husband celebrated their first Christmas together as a married couple.
Gwyneth Paltrow
The Goop founder spent Christmas morning with kids Apple, 19, and Moses, 15, who she shares with ex Chris Martin.
The Beckhams
Victoria Beckham and David Beckham appeared with three of their four kids—Cruz Beckham, Harper Beckham and Brooklyn Beckham—and daughter-in-law Nicola Peltz Beckham in a holiday pic the fashion designer shared Dec. 23.
Paris Hilton
The Paris in Love star took her and husband Carter Reum's 13-month-old son Phoenix to Disneyland on Christmas Eve.
Olivia Rodrigo
Christmas proved to be good 4 the singer, who rang in the holiday with Guts-themed ornaments.
Kelly Ripa & Mark Consuelos
The daytime talk show co-hosts were feeling the "Big Nick Energy" on Christmas.
Jesse Tyler Ferguson & Justin Mikita
"Merry Christmas & happy holidays from the Mikita - Ferguson household," the Modern Family star captioned this sweet photo with their kids Beckett, 3, and Sullivan, 13 months.
Reese Witherspoon
The Oscar winner showed off her dinner table setting, writing on Instagram, "Merry Christmas from my family to Yours."
Ariana Grande & Frankie Grande
The brother-sister duo rang in Christmas with their mom Joan Grande.
Heidi Montag & Spencer Pratt
No one else can feel the Christmas spirit for you—just ask the Hills couple and their sons Gunner, 6, and Ryker, 13 months.
John Travolta
The Grease alum went skiing with his kids Benjamin, 12, and Ella, 22.
John Stamos
"Merry Christmas everyone, and HAPPY HOLIDAYS!" the Full House actor captioned this family photo with wife Caitlin McHugh Stamos and 5-month-old son Billy. "Let's remember, the true spirit of Christmas lies not just in celebration, but in reaching out, in understanding and in caring for each other. Here's to going back to the beginning - to love, kindness, and compassion."
Lily Collins & Charlie McDowell
The Emily in Paris star and her husband woke up on Christmas morning to isses from their dog. "Merry Christmas, everyone!" she wrote on Instagram. "From our lil family to yours."
Jana Kramer & Allan Russell
They got the boy for Christmas! The singer and her fiancé snuggled with their newborn son Roman.
Chrishell Stause & G Flip
The Selling Sunset star and the musician celebrated their first Christmas as a married couple in Australia.
Jessie James Decker & Eric Decker
The pregnant singer and her husband celebrated their "last Christmas as a family of 5" with their kids Vivianne, 9, Eric "Bubby" Jr., 8, and Forrest, 5, in matching PJs.
Kathy Griffin
It looks like the comedian made Santa's naughty list, captioning this photo from Jesse Tyler Ferguson's holiday bash: "Yes, I was THIS old gal at the kids Xmas party. I’M PROUD OF IT!!!"
Heidi Klum & Tom Kaulitz
The supermodel and the Tokio Hotel rocker had Christmas at the beach.