он изменил

he cheated (on someone)

→ он
phrase Uncommon #15,710
he cheated (on someone) In this sense, the person he cheated on is usually expressed with a dative pronoun or noun. The phrase can also mean “he changed” in other contexts.
RU: Он изменил своей девушке.
EN: He cheated on his girlfriend.

А что он изменил?

And what did he change?

— Сельма (2014)

Он изменил жене.

He cheated on his wife.

Мэри изменила Тому, а потом он изменил ей.

Mary cheated on Tom, and then he cheated on her.

Он изменил моей матери.

He cheated on my mother.