The Story Behind J Lo’s Major Wedding Dress Moment in “Marry Me” 

"When you work with somebody who's at the level of Jennifer, you have to bring your A-game every second of every day," says Caroline Duncan, the ultra-talented costume designer who kept J.Lo looking fabulous in every frame of her new rom-com "Marry Me." "She cares so much about the visual, and she has a real feeling for it." It was a thrill, Duncan tells POPSUGAR, "to collaborate with someone who has such an understanding of fit and storytelling through clothing… Jennifer is an amazing choreographer of all moments."

Duncan was tasked with an interesting challenge when she joined the crew of "Marry Me." The costume designer, who has worked on productions helmed by Ava DuVernay, M. Night Shyamalan, and Steven Spielberg, to name-drop just a few lines from her impressive resume, was given the ultra-meta job of dressing a fictional pop star played by one of the most famous non-fictional pop stars of our time.

"The character is not Jennifer but has a lot of overlapping characteristics with Jennifer… so she brought so much to the table in terms of the nuances of the private life versus the public life of a pop star," explains Duncan. Though Duncan has had ample experience as a costume designer, working on this movie challenged her to think more like a stylist, since Lopez's character Kat Valdez would be dressed by a stylist. "It's a kind of meta experience as a costume designer," Duncan says. "I worked closely with Jennifer's stylists who were so helpful and generous in catching me up to speed in what it would be like to be a stylist for a pop star, which is a very different job than what I normally do. It was really fun to wear a different hat."

The swoon-worthy wedding dress that Lopez wears as Kat Valdez is so spectacular that the movie itself can't wait to reveal it — the title credits aren't even over before we get to gasp over its beauty.

"The idea for the wedding dress was to have a centrepiece for Kat's performance, her stage wedding, her public wedding that would feel part performative costume, part the most exaggerated and romantic Cinderella-wedding-gown anyone has ever worn; and then also supremely aspirational, as only a pop star would ever have a need for a dress of this nature," Duncan says. The dress they chose was one that Lopez had spotted in designer Zuhair Murad's runway bridal show. "There were a few dresses that she loved from that collection, but this was the one that really spoke to us," Duncan says. "The fact that the dress wasn't white was a huge factor in why we all fell in love with it. It's a rose gold with champagne notes, and it felt like it was for a woman who has been married a few times and a woman who is getting married under lights and on the stage, there was just an extra element of blush and sparkle."

And beyond the "blush and sparkle," there's some major drama brought by a giant, glittering, fairytale ball gown. "The drama of it was certainly part of the allure and part of what we gravitated to when we landed on it as a team," says Duncan. "And the volume of it — so dramatic. The dress is comprised of over nine layers of horse hair and tulle, and has a 25-foot train. The veil itself is something like 20 feet long."

It turns out, Kat Valdez's dress has some metaphorical layers hidden among the many literal layers of tulle.

"It's also really conjuring what is happening to her," Duncan tells POPSUGAR. "The dress really takes over the wedding. And then when her fairytale doesn't happen and she marries a stranger publicly, there's something very stifling and claustrophobic about the dress. Like she can't get away from the public's face, she's in the biggest dress that's ever been worn."

While the cast and crew agreed the wedding dress was a show-stopper, it also required a lot of attention. "The practicality of the dress, nobody loved," Duncan says with a laugh. "Because it's so big it took like five people to carry it and put it on Jen."

Another challenge for Duncan was building an on-stage wardrobe for Kat. Those pieces didn't just have to look good, they also had to keep up with Lopez's high-powered choreography and move with her. "Those looks are all breathable dance fabrics," says Duncan of the secretly utilitarian pieces. "They're all performance looks."

Some of the most dynamic scenes in "Marry Me" are the ones where Lopez performs her new, original songs on stage as Kat Valdez, including a high-octane, dangerously sexy performance of "Church."

"The idea for the 'Church' costume was that it was a number [Kat Valdez has] been doing forever," explains Duncan. "That was her first single, so this is a routine and a song that she's expected to play at every concert." The costume hints at Valdez's storied career without having to waste any lines of dialogue. "The look probably changes every few years for that number, but it's a look that feels like it has evolved a bit. Even though you never see the original version of it, you can imagine what the version from 15 years ago would be."

Flanked by praying nuns dressed in latex bodysuits (which were "a lot of fun!" according to Duncan), the whole number is a seductive frenzy. "It's provocative, and far more provocative than anything she'd wear in the street. The idea is she's at her most provocative, her most pop star, when she's performing."

If that stunning, gemstone encrusted bodysuit J.Lo wears is reminding you of another iconic fashion moment, you are totally correct. When asked if Duncan and her team were inspired by the bedazzled Christian Lacroix jacket Michaela Bercu wore on the November 1988 cover of Vogue (Anna Wintour's first issue as editor in chief), Duncan confirms it was "definitely a reference point."

Another powerful reference point for Kat Valdez's on-stage looks: "Really iconic Thierry Mugler from the '80s." For a duet with her ex, Bastian (played with plenty of ready-to-ruin-your-life energy by Maluma), she appears in a gold and silver gown layered with fringe and goddess-like accessories. "There were a lot of Thierry Mugler [references] in her headpieces and her jewellery," Duncan says.

Off-stage, Kat is allowed to drop her flashy celebrity armor. There's a trend-free normalcy to her outfits — even though they're still perfectly tailored and lushly rendered in silks and cashmeres. "In general, we wanted Jennifer's non-performative, non-stagewear aesthetic to be really timeless," Duncan says. "Old Hollywood, iconic, chic. So that if this movie is on in 10 years, you're watching it and not really caught up in the moment of the fashion. We didn't want anything to feel too on-trend, or too specific to when we were filming. We wanted it to stand that test of time so it would always feel elegant, chic, and aspirational."

Lopez plays Kat Valdez with a beautiful and relatable blend of confidence and insecurity — a juxtaposition that is reflected in her wardrobe. "She does have a lot of moments of vulnerability, and I think we put her in silhouettes for those moments that were able to bridge both things. She was able to look fierce and camera-ready — ready for her videographer to take coverage of her, ready to be snapped by the paparazzi — but also vulnerable," explains Duncan. "An example [of that] would be when she goes to the high school and meets Lou [Charlie's daughter, played by Chloe Coleman] for the first time, and she's in that all white outfit that has that little cropped, structured blazer. It feels really confident, she has fun sunglasses. It definitely feels like a look that she put together knowing it would be photographed, but she's also meeting Charlie's daughter and she wants to look more normal. And that's her version of dressing down and being normal. But it's still so powerful and chic."

Another example Duncan loved creating: "When they go back to her apartment and she's just in the shell turtleneck, she feels so relatable. It has a vulnerability to it, in that scene with her and Lou." That vulnerability is reflected as Lopez's Kat and Coleman's Lou are slowly opening up to each other, letting their guards down. Kat sheds her (literal) layers of clip-in extensions and blazer to have an honest heart-to-heart with her boyfriend's daughter. The visual matches the emotion: Her costume is transforming as she is. "That's an example of when the costume has an arc and serves both intents."

Kat's ultra-romantic look to chaperone her beau's high school dance had a personal backstory for Lopez. "That dress was born out of a conversation I had with Jennifer about what she wore to her semi-formal or prom. She made it for herself!"

The dress also struck the perfect balance of being special enough for an iconic pop star to appear in, but also approachable enough to not alienate the wide-eyed teenage fans at the dance. "That dress was perfect," says Duncan, who noted that it had a special "sweetness." "It had the shape of a pop star trying to be more grounded but it's still got a really, really flirtatious cut-out and is still something that a teacher at the school wouldn't wear to the semi-formal. But for Kat, it's way more relatable and feels much less presentational, less red carpet than her other pieces, but it still feels like a pop star's dress."

Another emotional arc Duncan's costumes telegraphed: Kat falling in love. "We had a colour chart, Jennifer and I," Duncan explains. "Where we started her [wardrobe] out with a lot of whites and metallics, and then her palette softened." As her romance with Owen Wilson's Charlie Gilbert deepened and warmed, so did her fashion. "We crept in blues and pinks and saturated her." That wordless storytelling is a hallmark of Duncan's impressive work as a costume designer.

"Marry Me," featuring Caroline Duncan's fabulous costumes and J.Lo's sincere performance, is in theatres nationwide and streaming on Peacock starting Feb. 11.