彼(かの)女(じょ) kanojoは wa夫(おっと) ottoが ga亡(な)く()な()っ()た() nakunattaと toいう iuこと kotoが ga信(しん)じ()ら()れ()な()か()っ()た() shinjirarenakatta。 She couldn't believe that her husband had passed away. Literal She [topic-は] husband [subject-が] passed-away [that-ということ] [subject-が] couldn't-believe. ~ということが信じられなかった — the entire clause 夫が亡くなったということ is nominalized by ということ and made the subject of 信じられない ('can't believe'). A layered construction. deathemotionsmarriage~ということだ (it means that)potential form (~える/~られる)
彼(かの)女(じょ) kanojoは wa夫(おっと) ottoが ga亡(な)く()な()っ()た() nakunattaと toいう iuこと kotoが ga信(しん)じ()ら()れ()な()か()っ()た() shinjirarenakatta。 She couldn't believe that her husband had passed away. Literal She [topic-は] husband [subject-が] passed-away [that-ということ] [subject-が] couldn't-believe. ~ということが信じられなかった — the entire clause 夫が亡くなったということ is nominalized by ということ and made the subject of 信じられない ('can't believe'). A layered construction. deathemotionsmarriage~ということだ (it means that)potential form (~える/~られる)