Helga,,,
Learning Russian, is necessary, only if the man is going to live with, his woman in Russia.
If not, he should absolutely not learn Russian, till after his woman, speaks fluent, the native language of the country, where they live.
The more he knows Russian, the longer it will take, for his woman to be independent, by mastering the new language.
I have been writing, some long posts, about this earlier.