In the episode "The Launch Acceleration", Amy tries to use her "neurobiology bag of tricks" to increase the attraction between herself and Sheldon. In the final fifth-season episode "The Countdown Reflection", Sheldon takes Amy's hand as Howard is launched into space. In the sixth season first episode "The Date Night Variable", after a dinner in which Sheldon fails to live up to this expectation, Amy gives Sheldon an ultimatum that their relationship is over unless he tells her something from his heart. Amy accepts Sheldon's romantic speech even after learning that it is a line from the first Spider-Man movie. In "The Cooper/Kripke Inversion" Sheldon states that he has been working on his discomfort about physical contact and admits that "it's a possibility" that he could one day have sex with Amy. Amy is revealed to have similar feelings in "The Love Spell Potential". Sheldon explains that he never thought about intimacy with anyone before Amy.
Leonard's mother Beverly visits, and he is thrilled when she takes an interest in his work. However, when he learns that she is doing research on him for a new parenting book, he is furious. He prepares to tell her how she let him down over the years, but instead chooses to accept and forgive her, and forgive himself for holding onto that resentment for so long. Beverley is touched that he forgave her and they share a genuine hug. Meanwhile, Anu gets a job offer in London. Raj prepares to fly out and propose to her, ready to follow her if she accepts. Howard stops Raj at the airport, saying there is a better match out there for him, convincing Raj to return home. Stuart and Denise are bothered by her creepy roommate Mitch, while Bernadette and Howard are tired of Denise constantly staying overnight with Stuart at their house. Stuart says he is ready to move in with Denise, and they say they love each other while convincing Mitch to move out.
Producers, writers and others, including recurring guest star Wil Wheaton, joined the festivities on set and — hardly a spoiler alert — more laughing, crying and hugging ensued. Lorre embraced a happy Parsons, then moved on to each cast member as if it were a reception line. Galecki shared long, emotional hugs with his colleagues. After trying to keep their emotions under control for so long, it was finally time to just let go.
Sheldon and Amy are surprised to find that Wil Wheaton's new Professor Proton show is actually very entertaining and that Wil had Howard on as a guest. On Howard's suggestion, Sheldon apologizes to Wil, mending their friendship, and tells him he wants to be on the show; but Wil asks for Amy. Sheldon tells her to do it, but she says she often doesn't do things to avoid upsetting him. Sheldon is horrified when he realises how selfish he has been, especially when he finds out that the men do the same for him. Sheldon encourages Amy to go on the show to inspire girls to pursue science while trying to control his obvious jealousy for her. Meanwhile, Leonard writes a book about a physicist that solves a murder, the protagonist Logan Dean is based on himself. Bernadette points out Logan's mean boss Illsa is similar to Penny, who thinks it is based on Bernadette, though Leonard does not correct her. However, Bernadette tells Penny the truth, upsetting her and making her mad at Leonard. After calling his mother for advice, Leonard learns that Illsa is actually like her; but abandons the book when he realizes he wrote romantic tension into the relationship between the characters.