The idiom is used when you want to emphasize
1. that both parties involved in a difficult situation must accept the blame, or
2. that an activity needs two people who are willing to take part for it to happen.
- From online, with editing
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Our newly elected Prime Minister Mark Carney stepped into "the lion's den" 
4 days ago for his first face-to-face with US President Donald Trump.
I have no idea what was discussed "behind the closed door", but found this YouTube clip (see below) very interesting.
In it, Trump said "It takes two to tango", adding "as a real estate developer at heart" he would love to see the U.S. span from the Gulf Coast to the Arctic Circle. "I do feel it's much better for Canada,"
Carney diplomatically shot down Trump's talk, saying that as a property developer he should know "there are some places that are never for sale."
Still, the president held out hope it might happen one day. He said "never say never" about uniting the two countries.
In response, Carney said: "Never, never, never, never, never," as reporters shouted questions (it's not in the video, but reported by CBC).
Haha, what a perfect example to illustrate "It takes two to tango" 
Have a fun weekend everyone!
