The Good Wife series finale - The creators have admitted that they planned out Alicia getting slapped by someone as the final scene... ever since the first season. They clearly reverse-engineered this finale just for that one moment, coming up with plot points that made no sense and giving us an ending that made the main character look awful. We'd really hoped for better from such a smart, amazing show.
Kalinda: How're you liking the prosecutor's office? It seems to agree with you. You look taller. Cary: I like the moral clarity. (he walks up to her) Do you miss me? Kalinda: What if I said yes? Cary: Well, I'd say, "That sounds about right." Kalinda: Then... yeah.