The Truth About Forever is a young adult novel that tells the story of Macy Queen, a teenager whose father has just died, turning her world upside down. She gets a summer job at Wish Catering, where she meets Wes, a reformed delinquent who begins to win her heart, and begins to make friends with her eclectic group of co-workers. This coming-of-age tale explores the difficult task of moving on after the loss of a loved one, and the wonderful things that can occur when you decide to open your heart again.
Macy is still recovering from the sudden loss of her father. Since he died during one of their habitual morning runs, Macy gives up running and keeps all of her feelings to herself. This results in her being unable to comfort her mother. Her boyfriend, Jason, is currently away at Brain Camp. When Macy attempts to communicate with him about her unhappiness with her coworkers at the library. At the end of one of their e-mails she tells him that she loves him, he replies and thinks it would be for the best if they took a break until he returns in August.
Upset and hurt, Macy goes for a ride and sees a van for Wish Catering, which catered her mother's party. She applies for a job, which she gets. Macy enjoys this new job and her new coworkers. There she meets the artistic Wes, who she later discovers lost his mother to cancer and attended reform school for breaking and entering. During this time Macy's older sister begins to renovate their father's beach house despite reluctance from the other family members (mainly from her mother). Her mother refuses to talk to Macy about the sudden death of her husband, Macy's father; therefore she proceeds to put all of her time into her work.
Macy attends a party with some of her coworkers, where a drunk, former friend from the track team reveals to Macy's friends Wes, Kristy, Bert, and Monica that she had to witness her father's death. Ignoring this information, everybody returns to the party. There, she bonds with coworker Kristy, who advises her to enjoy her life because forever keeps changing. Later Wes and Macy end up stranded together after their catering van runs out of gas, where Macy opens up to Wes about all of the issues in her life during a game of "Truth". They continue to play the game later during work, where Macy discovers that he is also in an "on break" relationship with a girl named Becky.
As Macy and Wes grow closer together, Macy's mother advises against the job and any possible relationship with Wes after Macy misses one of her mother's parties due to the birth of Avery, Delia's daughter. Macy later ends up deciding to confess to Wes that she cares about him, but sees him with Becky (Wes's girlfriend) and ends up heart-broken again. Her mother has Macy helping her with preparations for a party, but eventually has to have Wish Catering assist her. It is during this time that Macy succeeds in being able to comfort her mother and discovers that Wes has broken up with Becky.
Macy realizes that there's more to life than just sticking to the rules and trying to please everyone around her. She realizes that she's the only one in control of her future, and she chases after Wes as he leaves and they share a kiss. Wes and Macy become a couple, with her resuming her running habit with him. At the end of the book, Wes later joins her and her family at the beach house that has now been renovated.