There are also other ways to show respect for the partner in an internatinal relationship, and learning the language, if not living in the related country, is (nice, but) not a must. Moreover it is clear that Slavic languages present a challenge for learners.
Unfortunately those who are willing to make a step towards their possible wife's culture (at least to understand the differences and not expect her to behave like an emancipated Western lady) are really not many. Some communicate as if they were doing a great favour. That just bewilders and surprises me, and I get curious what are the advantages underlying such a position (no kidding, I would really like to know).
But, there is a positive side of it: the nicer look those who stay polite and respectful.