didn't understand
Том не понимал, почему Мэри себя так вела.
Tom didn’t understand why Mary was behaving that way.
Я не понимал, как мне повезло.
I didn't realize how lucky I was.
— Дом странных детей Мисс Перегрин (2016)
I never understood them.
Том не понимал.
Tom didn't understand.
I didn’t understand that either.
I really didn't understand.
Том, похоже, меня не понимал.
Tom didn’t seem to understand me.
I never understood him.