The American Roommate Experiment (2022) is a contemporary romance novel by Elena Armas. This New York Times bestseller follows the coincidental romance between the spontaneous but uncertain Rosie and Lucas, her best friend Lina’s cousin—a man she’s ogled from afar via social media—as they find themselves being roommates. With a few recurring characters, it is technically a follow-up novel to The Spanish Love Deception (2021), which was also a New York Times bestseller and, as of 2023, is slated for a film adaptation.

This guide is based on the Kindle e-book edition.

Plot Summary

The American Roommate Experiment opens with Rosie Graham facing a series of calamities: Her apartment ceiling collapsed due to flooding, so she is staying in her best friend Catalina “Lina” Martín-Blackford’s apartment. Lina, the protagonist of Elena Armas’s previous novel, The Spanish Love Deception, is on her honeymoon in Peru. Suddenly, a man arrives and tries to enter Lina’s apartment, claiming he has a key. Rosie mistakes him for a burglar, but after some banter, she realizes the man is Lucas Martín, Lina’s cousin. Rosie has been following Lucas’s social media, hoping to meet him at Lina’s wedding, which he did not attend. Lucas is friendly and charming, and when he realizes Rosie is uncomfortable, he insists she stay in the apartment and he go to a hotel. She reassures herself that the two will not meet again.

The next day, Rosie prepares to visit her father in Philadelphia, hoping to tell him and her younger brother, Olly, that she has left her engineering job to pursue writing and has recently been offered a publishing deal. She is an avid reader-turned-writer of romance novels but knows her father is proud of her stable engineering career. She spots Lucas in a diner and realizes he slept there. The two chat over breakfast, and Rosie shares her anxieties about her career change, while Lucas is cagey about why he left Spain for a three-month trip to the United States (explaining his absence from Lina’s wedding). Later, Rosie notices her brother, Olly, avoiding discussion of work and finds herself unable to tell their father about her career change when he is clearly worried about Olly.

Upon her return to New York, Rosie and Lucas decide to share Lina’s apartment—without notifying Lina, as she is on her honeymoon. They are both attracted to each other, but each privately decides to stay friends. They befriend Lina’s neighbor, Adele, an older woman living with dementia. Lucas impresses Rosie with his cooking. After a frustrating day arguing with her landlord over apartment repairs, Rosie confesses that she has barely written any of her book, which is due in eight weeks. Lucas overhears Rosie on the phone with Lina, pondering a return to dating in the hopes of inspiring Rosie’s manuscript. She is pessimistic about this, as her dating history is full of disappointment. Lucas offers to be her partner in a dating experiment, constructing ideal dates so Rosie will not have to involve strangers. Because she still has a crush on him, Rosie agrees.

Lucas plans their first date to a record store, where Rosie selects ABBA’s “Dancing Queen” for their soundtrack. They dance and flirt but are soon interrupted when a rat comes out of a record player box. Their second date involves making pizza, during which Lucas explains that his surfing career is over because he injured his leg. The pizzas burn as the two almost kiss. Lucas castigates himself for failing to be the perfect boyfriend, but Rosie assures him that he surpasses her exes. Meanwhile, she continues to worry about Olly, who has a job at a nightclub with men who appear threatening to his safety.

Lina eventually returns, stunned and disappointed to find that Rosie and Lucas are living together and said nothing. She worries Lucas will hurt her best friend with a casual relationship, but they assure her that they are just friends. She confides to Rosie that her family is worried about Lucas, leading Rosie to realize she is the only one who knows about his accident and related panic attacks. Adele’s daughter, Alexia, comes over for dinner and suggests to Lucas that he train as a chef, but he dismisses the idea.

Rosie and Lucas attend a Halloween masquerade ball with Lina and her husband, Aaron. When Rosie is soaked by a stranger’s drink, Lucas helps her clean up, and the two nearly pursue the sexual attraction between them until Lina interrupts. Lucas is clearly jealous when he sees another man ask Rosie out, and she also feels conflicted. He softens when he learns she organized the arrival of his sister, Charo, and dog, Taco, to help him with his panic attacks. Meanwhile, Rosie’s writing improves, inspired by her dates with Lucas.

During Rosie and Lucas’s third date, Rosie confesses her romantic attraction. They embrace but are interrupted when Olly begs Rosie for help. Rosie and Lucas learn that Olly has been working at an adult entertainment club. They rescue him from the club’s cruel owners, and Lucas is injured in a scuffle—leading Rosie to feel guilty. Rosie and Lucas slowly become a couple. She returns to her repaired apartment but soon summons Lucas. Lucas claims he does not deserve her as a man with no career prospects but reciprocates her love. They have sex and spend Lucas’s last week in New York together. Rosie also finishes her book and thanks Lucas for his help.

Rosie follows Lucas to the airport, confessing her love and offering to go to Spain with him—but he refuses her offer. He still sees himself as unworthy of her devotion. Rosie is devastated, and Lina apologizes for not supporting her sooner. Lina reads Rosie’s book and calls Lucas, telling him that as angry as she is at him for hurting Rosie, Rosie’s book is proof of his worth.

On New Year’s Eve, a pessimistic Rosie agrees to attend a party with Lina and Aaron. Lucas surprises her at the stroke of midnight, explaining that he felt unworthy of her but now understands that he needs to face his past. He is seeking therapy and plans to pursue culinary school in New York to be with her. Overjoyed, Rosie accepts his offer. In the Epilogue, Lucas arrives in New York a year later, ready to move in with Rosie and begin his new life.