The Russian Orthodox Church is a very funny institution. The Church, for instance, allows people to marry even if they are married to somebody else legally. Also, the Church allows people to get divorced up to 3 times (or an infinite number of times if you are willing to pay a fee.) While you are getting married and divorced in the Church, you can absolutely keep getting married and divorced with other people legally.
As a result, it is possible to have two sets of rotating spouses that change every couple of years and exist independently of each other. The system exists to accommodate the Russian nouveau riches who can’t marry their endlessly swapped mistresses legally and pacify them with the “more spiritual” Church weddings.
Obviously, the Russian Orthodox Church is horrified with how the evil Westerners degraded the sacred institution of marriage by granting gay people the right to marry. Obviously.