Kohl's office said the 78-year-old Kohl and Richter, 44, were "very happy."
Kohl, a widower, has been in a Heidelberg clinic recuperating from a fall and subsequent surgery, Deutsche Welle said Tuesday.
Kohl led Germany's reunification in 1990 and left office in 1998. He confirmed in 2005 that he and Richter, a government economist, had been living together.
Notable deaths of 2014 [PHOTOS]