Sarah and Brianna have always been friends, and it's always gone like this: guys talk to Sarah in order to get closer to Brianna. So even though Sarah met Ryan first, she's not surprised that he ends up with Brianna (even though Sarah has a massive crush on him). The three of them hang out, and Sarah and Ryan's friendship grows until one night an innocent exchange between them leads to a moment that makes Sarah realize that Ryan might be interested in her after all. But if there's one unwritten rule, it's this: you don't mess around with a friend's boyfriend. So Sarah tries to resist temptation. But with the three of them thrown together more and more, tension builds between Sarah and Ryan, and when they find themselves alone together at one point, they realize they just can't fight how they feel anymore....
In a smart, well-observed story about the intricacies of teenage love and friendship, 17-year-old Sarah has always been in the shadow of her beautiful best friend, Brianna. And Brianna makes sure she stays there with such comments as, "You're tiny and quiet, so guys never notice you. It's because they're stupid and only think about looks and stuff, of course, but still." After Brianna swoops in and snags Sarah's longtime crush, Ryan, at an end-of-summer party, Sarah can't help but break the titular unwritten rule: "I'm that girl. The one who likes her best friend's boyfriend. In the world of friendship, I'm awful." Brianna relies on Sarah's help to cope with her parents, so Sarah does all she can to quash her feelings, but she can't help kissing Ryan, who slowly reveals his true feelings. The story line is not new, but Scott (Something, Maybe) brings her usual sharp dialogue and fully formed characters to the script (especially earnest, conflicted Sarah, but also secondary characters such as Sarah's mother, who participates in competitive cook-offs), making it feel fresh. Ages 14 up.