German rower Nadja Drygalla left the Olympic village on Friday following reports that her boyfriend was a far-right extremist.
The German Olympic Committee said Drygalla, who had already finished competing at the Games as part of the women's rowing eight team, left of her own accord after a 90-minute conversation German officials.
"Miss Drygalla confirmed credibly her commitment to the Olympic Charter," the head of Germany's committee Michael Vesper said. "She is leaving the Olympic Village so as not to be a burden for the team."
Though German officials did not give the reason for her departure, referring only to findings on the athlete's "private environment", German public broadcaster ARD reported the 23-year-old former police officer was suspected of sympathising with right-wing extremist ideology.
Media reports said her boyfriend was a leading member of the "Rostock National Socialists" and had fought a state election for the far-right National Democratic Party (NPD).
Germany's intelligence agency describes the party as racist, anti-Semitic and inspired by the Nazis. Its local election campaigns blame immigrants for crime and unemployment and its supporters are mostly unemployed young men with little education in depressed areas of the east.
It is represented in two state assemblies - the east German states of Saxony and Mecklenburg-Vorpommern - but not in the federal parliament.
One attempt to ban the NPD failed in 2003 after witnesses were exposed as intelligence agency informants.
A country whose history means there is no tolerance in mainstream politics of neo-Nazi sympathies or anti-Semitism, Germany has been rocked by the so-called "doner murders" of nine Turkish and Greek immigrants carried out by a neo-Nazi cell between 2000 and 2007. Authorities only discovered the cell by chance late last year.
The German rowing federation said in a statement it welcomed Drygalla's decision.
"We will have another conversation with Nadja Drygalla in August after the Olympic Games. After that we will decide together with her how to proceed," said Siegfried Kaidel, the head of the federation.
Mark Adams, spokesman for the International Olympic Committee, said Drygalla had done nothing wrong at the Games: "There is no issue for us regarding the rower. I have seen the report. But as far as the Games are concerned, she has not done anything wrong."