No Boy Summer — Amy Spalding

In Amy Spalding's young adult novel No Boy Summer, Lydia and her younger sister, Penny, make a pact to avoid boy drama for the summer -- but Lydia can't help looking for a loophole when she falls for a cute girl.
 
Lydia Jones and her younger sister, Penny, have had it with boy drama. Last year was marred by relationship disasters for both of them, threatening Lydia's standing with her school's theater tech club and Penny's perfect GPA. Penny has, naturally, diagnosed the problem and prescribed a drastic solution: a summer off from boys.
 
Deciding to stay with their Aunt Grace and her boyfriend, Oscar, in Los Angeles while their parents are off on a European cruise, Penny follows her future business-school dreams with an internship at Oscar's office, and Lydia gets a part-time job at Grace's neighborhood coffeeshop, Grounds Control. Even when they spent hours, days, weeks dissecting their various boy drama, Lydia's never felt this connected to her sister before, and it makes her wonder what else in her life could be different. She finds herself drawn to a group of friends she meets through her Grounds Control coworker Margaret, as well as an intriguing customer, Fran, an aspiring filmmaker and -- while not the first girl Lydia has found herself attracted to -- the first girl who has mutual feelings for her. But she's not breaking her pledge to Penny, right? That was just about boys.
 
Even though in her heart Lydia knows she's bending the rules, she hasn't had a connection with anyone as strong as her connection with Fran, so she thinks it can't be wrong. And Penny won't mind as long as she's happy . . . right?