поверить не мог

couldn't believe it

→ поверить
phrase Rare #46,096
couldn't believe it An emphatic expression of disbelief. The masculine past-tense form мог indicates a male speaker or subject; a female speaker would say поверить не могла. Often used with ушам своим to mean “couldn't believe one's ears.”
RU: Я поверить не мог, когда узнал эту новость.
EN: I couldn't believe it when I heard the news.

Я поверить не мог.

I couldn't believe it.

— Малхолланд Драйв (2001)

Он ушам своим поверить не мог.

He couldn't believe his ears.

Я ушам своим поверить не мог.

I couldn't believe my ears.

Да, я поверить не мог.

Yes, I couldn't believe it.

— Ларс и настоящая девушка (2007)