My Sister's Boyfriend — Katherine Applegate

Justine Drew is a skeptic about romance. She's had only one love-a mysterious stranger on an amusement-park ride-and she never expects to see him again. Justine's beautiful younger sister is the opposite: She falls in love weekly. So when Skyle says she finally found true love Justine doesn't believe her-until Skyler brings her true love home. Rick Callahan is Justine's own mystery man, and Justine's feels her heart breaking the moment she sees him.

Justine vows to keep her distance from Rick, but when he's cast as the leading actor in a prize-winning play she has written, that vow is impossible to keep. If only Justine could write a happy ending to her own real-life tragic romance...