Cardcaptor Sakura - Season 3 Episode 19

Toya and Yukito are starring in an independent film directed by Nakuru for their school fair, and Nakuru gives Sakura a role. Sakura later begins to notice that Yukito is losing his power and is starting to fade away. Things come to a head when Yukito passes out and falls of a veranda while shooting the film, though he is saved by Toya and, secretly, Sakura. Toya finally manages to tell Yukito the truth about his power, telling off Nakuru when she attempts to interfere. In order to maintain Yue's power and existence, thus allowing Yukito to survive, Toya sacrifices his powers to save him, though losing the ability to sense when Sakura is in danger. As such, Toya has Yue promise to protect Sakura, as well as himself. Having overheard, Sakura realizes that Toya had indeed known about her secret all along. She confronts Kero about why he didn't tell her about Yue/Yukito; Kero explains that he did so to prevent her from blaming herself, since her power alone wasn’t enough to sustain him, and thus act irrationally because of it. Not wanting Yukito to disappear again, Sakura resolves to confess her true feelings to him.