From the first sentence of the second paragraph of the article, and I quote:
It is utterly improbable that David Michael Miranda, a Brazilian national transiting through London, was detained at random, given the role his husband has played in revealing the truth about the unlawful nature of NSA surveillance,
He’s not partnered with Snowden.
He’s the partner of Greenwald, the journalist that wrote the articles re: Snowden’s revelations.
http://www.popsugar.com/Edward-Snowden-Girlfriend-30775813
/johnny
Miranda is married to Glenn Greenwald, the Guardian journalist who analyzed and published information on documents leaked by Snowden.