The following version of this book was used to create the guide: Hazelwood, Ali. Love, Theoretically. Berkley Romance, 2023.

Elsie Hannaway is an adjunct professor of theoretical physics who works as a part-time fake girlfriend. Her current fake boyfriend, Greg Smith, is a kind young man who is concealing from his family that he is asexual. His brother, Jack, intimidates Elsie as she senses he sees through her fakeness. At the birthday party of Jack and Greg’s grandmother, Millicent, Jack and Elsie play Go. They tie. Jack catches Elsie not knowing about the retreat Greg is going on for his job.

The next day, Elsie attends a dinner hosted by MIT’s physicists. She is hoping to work there. A physicist named Monica warns her in advance about the rivalry between MIT’s theoretical and experimental physicists. Jack is at the dinner. Elsie had no idea he was really Jonathan Smith-Turner, who became famous years ago for publishing a bogus theoretical paper in a prestigious journal. Elsie’s mentor, Dr. Laurendeau, was the editor at the time.

Jack teases Elsie all night, culminating in a confrontation in the bathroom. Elsie tells him she hates him and vows to get the job. Jack tells her his candidate, George, will get it.

Elsie’s mom continuously calls her to solve a dispute between her older brothers. Elsie spends the following day giving a trial lecture at MIT, then having interviews with the staff. Jack shows her around and tells her he can tell she changes her personality to please people. Despite Jack’s brusqueness, Elsie enjoys his presence and honesty. She nearly faints in front of him, exposing her diabetes. That night, Monica hosts a party for the physicists. Monica’s son, Austin, calls Elsie a hooker in front of Jack. Austin tried to pay Elsie for sex years ago when they went on a fake date. Elsie explains the nature of her job. Jack defends her and threatens Austin.

The next day, Elsie gets a call from a dental office saying Greg had emergency surgery and needs someone to pick him up. She and Jack show up at the same time. They bring Greg home. Greg confesses to being asexual. Jack apologizes to Elsie for assuming she was a liar and only using Greg. Jack says he has always had a crush on her.

About a week later, Elsie runs into Jack at the movie theater. She is with her roommate while he is with George, his gorgeous female job candidate. George mentions she got hired by MIT. George did not realize Elsie had applied. Jack follows Elsie when she runs off and vows to explain everything at his place. He does so and says that MIT was always going to hire George. He thinks they were wrong to interview Elsie when she did not have a fair chance. Elsie spends the night in Jack’s bed because of the blizzard. In the middle of the night, she goes to the living room to apologize to Jack for misunderstanding the situation with George. He reassures Elsie that he will help her with her research. He says he fantasizes about taking care of her.

The next morning, they stop at Millicent’s before going to Elsie’s work. When left alone with Millicent, Elsie learns that Jack and Greg are only half-siblings. Jack’s mother, Grethe, was a theoretical physicist. His stepmother, Caroline, rejected him. That is why he is so obsessed with honesty.

Jack brings Elsie to a party for their first date. They get dinner afterwards and discuss Elsie’s relationship history. She fake-dated a guy in college who broke her heart. Elsie and Jack start dating consistently. George offers Elsie a place on her team.

One night, Elsie and Jack watch Twilight, her favorite movie. They have oral sex, but Jack does not want to have sex yet. Later that week, they enjoy a peaceful lunch with Greg and then have a sleepover. They have sex for the first time the following morning. Elsie changes her insulin pod in front of Jack.

At a party, Elsie overhears Andrea, Jack’s colleague, berating Jack for dating a theoretical physicist. After, Elsie asks Jack’s motivations behind publishing that bogus paper all those years ago. He says that Laurendeau ruined his mother’s career. Elsie feels like Jack lied to her and stops talking to him.
Elsie confronts Laurendeau, who calls her silly and stupid for believing Jack. A few weeks later, Elsie accepts George’s job offer and apologizes to Jack. Eight months later, they are in a happy and committed relationship.