In the process, she ends up shunning Brian (who has become one of her closest friends since the end of the first novel) when he visits her and makes a video which upsets her mother. In the end, she realises that Brian is her true friend, and Alex and Maura are phony. She makes a touching video about Bailey, and Brian and her mother forgive her. Brian asks Tibby to the senior dance at their high school, and she says yes. After the dance, at a picnic table, they exchange their first kiss, and Brian reveals his feelings for her. The next morning while thinking about Brian, Tibby forgets that her younger sister has been trying to get an apple from a tree outside her window. She opens the window, and her sister accidentally falls out. Tibby becomes depressed and blames herself, so she avoids Brian. Eventually, though, she comes to terms with her problems. Tibby ends up helping deliver Carmen's half-brother, Ryan and becomes his godmother. After that, she finds Brian, and together, they strip off their clothes and jump into the city pool, marking their start as a couple. Brian, Tibby's now long-term boyfriend, visits her and announces that he's been admitted to NYU, where she studies. Afterwards, they get drunk and have sex for the very first time. They discover that the condom broke, leading Tibby to suspect that she may be pregnant. Although she later finds out that she is not, she breaks up with Brian. Lena's younger sister, Effie, then seeks her out and asks her permission to go out with Brian. Tibby begins to doubt her decision to break up with Brian and becomes terribly upset. Lena then goes to Tibby's house to comfort her. They talk about their relationships and both come to a revelation, that they only fall in love once. Tibby meets Brian at the site of their first kiss, the picnic table, and apologizes for letting her fear ruin their relationship. They enter a new stage in their romance. This results in Effie taking the pants out of anger, and accidentally losing them in Greece. Ten years following the last sisterhood book, Tibby has moved to Australia with Brian and now has almost no contact with the three other girls. Soon after moving to Australia, Tibby learns that she is not only pregnant but she is also diagnosed with a terminal disease. She keeps the pregnancy a secret from the sisterhood and her family, as revealing it will also reveal the disease.