Gossip Girl: Serena and Dan
Lonely Boy (Dan) had feelings for Serena since he first bumped into her upon her arrival back. The duo were more than an on-again-off-again. They were that, plus, date-other-people-in-between, which turned into our-parents-are-dating-so-now-we're-step-siblings. Ultimately, Serena realizes Dan is her one true love and they get married in the series finale.