The Third Wheel: Diary of a Wimpy Kid (BK7‪)‬

In The Third Wheel, love is in the air—but what does that mean for Greg Heffley? A Valentine's Day dance at Greg's middle school has turned his world upside down. As Greg scrambles to find a date, he's worried he'll be left out in the cold on the big night. His best friend, Rowley, doesn't have any prospects either, but that's a small consolation. Then an unexpected twist gives Greg a partner for the dance and leaves Rowly the odd man out. But a lot can happen in one night, and in the end, you never know who's going to be lucky in love.
 
'Writing The Third Wheel has been a lot of fun because there's so much humor to be mined in the world of middle school romance. When the dust settles at the end of the seventh book, the Wimpy universe will be changed in a way that will surprise fans of the series.' says author, Jeff Kinney.