Well, Serena confesses her amor for Nate at the last book, but Nate texts both her and Blair that he's going sailing o something (meaning he won't fecha 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 amor You" is coming out this November. Only then will we know who Serena will be with. It could be Nate o it could be a new character. Who really knows. I guess the real answer is that we'll have to wait until the siguiente book comes out to see what happens then.