The couple married in 2014, exactly nine years after they tied the knot in a civil partnership ceremony.
The singer said he planned to discuss gay rights with Russian president Vladimir Putin over a cup of tea, he told The Sun.
Furnish recently took over the management of Sir Elton's business affairs and the pair have "changed some assistants".
But Sir Elton insisted that Furnish's decision-making was not unpopular with everyone and that record company Universal had never been happier.
In the interview, Sir Elton paid tribute to the couple's two sons and said they were behind his happiness.
"I love it over there but there's not enough irony there and it's not England. This country is absolutely lethal!," he said.
"Hence I don't go on Twitter. Things you say in jest, when you look at them in print, oh my God."
