She was a wonderful spouse who stood by him even when he was poor.
Literal
She [topic-は] [he [subject-が] poor [when-とき][even-も] he [object-を] support] wonderful spouse was.
A relative clause modifying 配偶者 ('spouse'): the entire 彼が貧しいときも彼を支える chunk describes what kind of spouse she was. ~ときも ('even when') adds the inclusive/contrastive も to the temporal とき, emphasizing 'even in hard times.' 配偶者 is a formal/legal term for 'spouse,' more bureaucratic-sounding than 夫/妻 or パートナー.