How Reformation and Rom-Com Red Became 'The Love Hypothesis' Fashion Formula

During The Love Hypothesis press tour, Lili Reinhart's red carpet and street style looks paid tribute to some of the most iconic fashion moments from '90s and 2000s rom-coms. But the Prime Video film, based on Ali Hazelwood's popular romance book, features a swoon-worthy wardrobe of its own.

In the movie adaptation, Reinhart plays Olive Smith, a biology PhD candidate at Stanford University. While lab coats are a fixture of her character's fashion (she wears one for almost half of the film's duration), outfits with splashes of personality emerge from beneath the coat's crisp white collar. "Science plays a role [in Olive's closet], but she's still a young student," costume designer Myriam Hanahem tells Marie Claire.

Whether Olive is working in the biology lab or faking her relationship with Professor Adam Carlsen, crop tops, feminine florals, romantic color trends, Adidas Samba sneakers, and linen-looking blouses are part of her regular rotation.

According to Hanahem, effortless French-girl fashion became the blueprint. "The mood board was a mix of vintage inspiration, like Jane Birkin on a bike, vintage dresses, the jeans and a T-shirt [uniform], just comfortable," she says.

Hanahem and Reinhart created "an organic collaboration" inside the film's fitting room: "She's been doing this for a while, so she knows her body, she knows what she wants, which is great," Hanahem adds. "She would try something on and then it [brought] us to something else, and then we mixed and matched things that we didn't think of at the beginning."

While the costume designer was, of course, inspired by the book, Hazelwood kept her characters' outfit descriptions to a minimum. Chapter 16's unicorn socks (IYKYK) scored a starring role in the film's sauciest scene, but beyond that, Hanahem trusted the actors to choose costumes that they felt their characters would wear in real life. "[It was important to] honor the people who play [the parts] so they're the most comfortable they can be," she says.

Receiving Reinhart's input led Hanahem to Olive's signature shade: red. The film's romance genre didn't inspire the 26-year-old character's go-to color, though. "It all started with the Isabel Marant cardigan," she says, remembering the strawberry-dyed sweater that Olive wears the first time we see her in the lab. (By the way, the Newton Cardigan is still available in a slightly darker shade.) "Then it became a red world," Hanahem adds. "In the fitting, we just kept going towards the red pieces."

On her first (faux) coffee date with Dr. Carlsen, Reinhart's Olive layers a ruby raglan tee beneath an identical crocheted cardigan. Later, at the faculty cocktail party, she makes quite an impression in a crimson-colored midi dress, courtesy of Reformation (Hanahem's preferred retailer for Olive's dresses).

"We would buy from [Reformation] and then just make [the look] our own, [either by] shortening it or changing a strap," she says. "We had more expensive pieces and then pieces that people could relate to because she's also a student with basically no money."

Speaking of Hanahem's favorite outfit from the film, during a picturesque post-party stroll with Dr. Carlsen, Olive layers a dark denim jacket over the spaghetti-strap, floral-print slip. "We tried a bunch of different jackets, [including] blazers, and yet we ended up with denim, because it's relatable and you can put higher-end pieces underneath and it looks like it's still something that people can afford," she says.

Olive wears red for some of the love story's most pivotal scenes, but the color wasn't right for a major moment in her career. So, Hanahem went with black. "At first, she wasn't supposed to be in black," she says. "We tried green and red [before deciding] that she should be in black, I think two or three days before the scene."

But because they were filming in Montreal, which "doesn't have that many stores," Hanahem flew to New York City for 24 hours to buy 15 black dresses. In the end, Reformation came to the rescue again, as the foundation of the look: "We changed it a lot—the length, the straps—we changed almost everything."

While presenting her research, Olive wears a "classic" black blazer by Theory over the LBD's V-neck. But why—after wearing bold blues, greens, and reds on repeat—did she switch to all-black attire? "Adam is always wearing black, so it's kind of like she meets him in his world," Hanahem says, reflecting on their (accidentally) romantic dinner scene.

Just like in any rom-com, all of these looks led up to the grand finale. "Everyone has the ending in their mind," Hanahem says. So, she asked herself, "How would most people picture Olive [during] the final kiss?" Once again, Hanahem went with a red Reformation dress, "but with a sleeve and something more casual compared to the other dresses she wore, because she knows her place now." And her wardrobe reflects that.