It is rude to spoil the ending of a show.
Jill is rewatching her favorite show with Jim, who hasn't seen it yet.
Jill wants Jim to know how the episode ends.
Jill waits and watches the show quietly with Jim till the end.
Jill reveals halfway through the show that the main character dies at the end of the episode.
Jim is amazed by the surprise ending of the episode becomes a huge fan of the show.
The episode is ruined for Jim, who soon loses interest in the show.