You Know You Love Me is the second novel in the Gossip Girl series. Written by Cecily von Ziegesar, it was published by Little, Brown in 2003.

Plot summary

This second novel began on Blair Waldorf's dad's advance birthday party at the Le Giraffe restaurant, together with Nate Archibald. Nate and Blair attempted to have sex again, but unfortunately it was held back because her mother, Eleanor Waldorf, was now engaged to her stubby boyfriend, Cyrus Rose, and even scheduling the short-notice wedding on her seventeenth birthday, ruining Blair's life more than ever, including her relationship with Nate.
In another setting, Serena van der Woodsen and Dan Humphrey were on an ice cream date, but nothing exactly comes of it, due to Dan's dark poetry, which starts to freak Serena out. She seems happy to remain as friends, even if she doesn't see him as boyfriend material.
To make things up for Nate, Blair decides to buy cashmere pajama pants but her credit card was invalid so she ended up stealing them, with Serena as an eye witness. Meanwhile, Nate meets Jenny Humphrey completely by accident and they start seeing each other behind Blair's back. Halfway through the novel, Nate, and a few of his friends, including Serena and Dan, go up to Brown University for their interviews, completely leaving Blair behind.
Aaron Rose, Cyrus' son and Blair's new stepbrother, moves in the Waldorf household with his boxer, Mookie. He drives Blair to her Yale University interview, but with her situation she is in, she ends up kissing her interviewer [on the cheek] and telling him the sad story, completely messing up her chance of getting in. Aaron and Blair become friends, despite the fact that Blair disapproves of their parents' marriage.
On the wedding day, though, things get a lot worse, because Blair finds out that Nate went out with Jenny when she caught them kissing in the hotel lobby where the reception was being held. She goes to the bathroom and bumps into Serena; they finally make up and became best friends again.