Suppose an American citizen is engaged to a Russian citizen. The couple would like to be able to live in America together. They do not particularly need to live together in Russia, although the Russian would like to be able to return from time to time to visit family etc.
In order for the Russian to come to the US, the American needs to approve a visa for the Russian to travel to the US, where they have 90 days to get married and the Russian can file for a change of status.
The part I don't understand is, what do we need from Russia? The Russian is obviously going to have to tell them "hey I'm going to the US to marry a guy, and I will be there indefinitely (though I am planning on coming back to visit family etc.)".
What process do they have to do on the Russian side?