The Brit introduced her sister Felicity to Tucci, her co-star in the 2006 comedy The Devil Wears Prada, and the couple started dating. Now they're engaged, according to reports.
Tucci recently proposed to Felicity, a literary agent, and she is planning to move to the U.S. to live with the actor.
A source tells Britain's Daily Mail, "They are extremely happy. Stanley lives in America and the plan is that Felicity will move there to be with him... It's perfect really, because Emily really missed her sister when she moved to America but now they will soon be together again."
Tucci was widowed when his wife Kate lost her battle with cancer in 2009.
Blunt wed U.S. actor John Krasinski last year (10).