Kristen (Clique Summer Collection, #4) by Lisi Harrison

With the rest of the Pretty Committee scattered across the globe, Kristen is stuck in summer school at OCD, making good on her scholarship commitments. No sleepover horse camp, no Hawaiian spa, no Spanish vacation, not even a trip to Orlando. But when Kristen scores a job looking after hang-ten hottie Dune Baxter's eight-year-old sister, Ripple, Westchester suddenly doesn't seem so bad. It looks like Kristin is about to ride the wave of first love. . .