In the book series Serena will end up with?

Well, Serena confesses her love for Nate at the last book, but Nate texts both her and Blair that he's going sailing or something (meaning he won't date either of them). So basically, Serena ends up with no one (definately not Dan since their relationship lasted about one and a half books). But the new book "I Will Always Love You" is coming out this November. Only then will we know who Serena will be with. It could be Nate or it could be a new character. Who really knows. I guess the real answer is that we'll have to wait until the next book comes out to see what happens then.

Serena end up had no one. Nate choose neither her or Blair. Blair had Chuck and Dan had Vanessa.