Marriage was supposed to bring them together. Instead, it was the beginning of a long ordeal apart. Germany blocked Nguyen from entering the country after she flunked the language test that Germany requires aspiring immigrants to pass - even those married to Germans.
"I thought marrying the person you love and living together was a human right," Guhle said in his modest two-room apartment on the outskirts of Berlin. "Apparently this is not the case in Germany."
Germany adopted German language regulations for prospective immigrants in 2007. Most EU countries - including France, Italy, Spain and Sweden - do not require foreign spouses to pass mandatory language tests before they join their partners in Europe. Austria, Britain and the Netherlands are among countries that require language tests before foreign spouses can enter the country, but experts say Germany's test is the toughest.
The European Commission has criticized the law in Germany, saying it may violate European treaties. And a legal challenge to the European Court of Justice is expected to be heard this month. As things stand, however, binational couples like Guhle and his wife face costly and daunting challenges.
Germany defends the law as a way to prevent forced marriages and to help immigrants integrate more easily. Critics maintain the law discriminates against the uneducated and poor. Most agree immigrants should learn German, but opponents of the law say that could be done more quickly, cheaply and easily in Germany.
"Well-educated people who can afford the language classes won't have any problems meeting the language requirements quickly - but not the others," said Hiltrud Stoecker-Zafari, the head of the national Association of Binational Couples and Partners. "Therefore we think: This country obviously wants to send out the message that financially weak and not well-qualified spouses should not even come here."
Fueling that argument are some of the exceptions to the German language proficiency rule: People with university degrees and people who have founded companies are exempt.
Another quirk: If a non-German EU citizen living in Germany wants to bring his or her non-German speaking spouse to the country, that's not a problem. A Frenchman living in Berlin could bring his Vietnamese wife to Germany immediately - but not Guhle.
"We only wanted to live together," said Guhle, a soft-spoken 43-year-old with a stubbly beard and warm gray-blue eyes. "How are you supposed to learn German if you are poor and uneducated and live in a remote Vietnamese fishing village?"
The government defends the measure, saying it requires only basic language knowledge - including conversational German and some reading and writing skills.
"If an immigrant doesn't have to start from scratch but already knows how to communicate, he will be more motivated to successfully work on his integration after he has received his visa," said a spokesman for Germany's Interior Ministry, speaking on condition of anonymity in accordance with ministry policy.
While the government does not have statistics to show how many forced marriages were prevented by the regulation, the spokesman said that authorities have repeatedly been told by German diplomatic missions abroad that victims of forced marriages use the language test as a way to avoid getting into an unwanted marriage.
"They repeatedly and on purpose fail the test to make sure they don't get a visa for Germany."
It is not clear how many couples have been separated by the law. According to the latest official statistics, some 40,000 people took the test at Germany's partially state-funded Goethe Institute language schools around the world in 2012. Of those, around 14,000 failed and would not have been able to obtain a visa.
When Guhle first went to Berlin's city hall in the fall of 2006 and said he would like to marry his girlfriend from Vietnam in Germany, an official told him - without explanation - that it wasn't possible. The couple then decided to have a traditional wedding with 300 guests in Nguyen's fishing village Doc Let. They got married in Vietnam in the summer of 2007 and planned to move to Germany straight away - not knowing that Germany had just enacted the language law.
Their relationship soon became a story of long stretches of loneliness - and thousands of euros in expenses.
Guhle, a low-paid nurse's assistant, took on a second job cleaning streetcars at night so he could finance his wife's German classes in Nha Trang, the nearest city where they could find a private German school. He paid for her hotel for nine months while she studied, and also financed the trip to Ho Chi Minh City where she would take the language test.
"These classes are unacceptable for people who are illiterate or come from rural areas," says Sevim Dagdelen, a Left Party lawmaker who has been lobbying to scupper the law. "There are many couples whose relations were shattered because of all of these burdens."
Nguyen failed the test and did not get her visa. She kept trying to learn German, but it was never enough. German authorities even refused to issue a tourist visa to let Nguyen visit her husband in Berlin.
"I reduced my life to working and visiting my wife on vacation. Every morning and night I would call her," said Guhle. "It wasn't easy for her either - people in the village gossiped about why the man from rich Germany wasn't able to come and take her home."
The couple took their case to a German court. After proving that Nguyen had repeatedly tried to learn German for over a year, she was finally allowed to immigrate.
She arrived in Berlin last September.
Sitting in their apartment, the two hold hands and talk to each other in a chaotic but fluent mix of English, German and Vietnamese. They call each other "honey" all the time.
"I'm so relieved to finally be in Germany with my husband," said Nguyen, a shy woman with long black hair. The 27-year-old has signed up for an intensive German language class and is eagerly looking for jobs at Vietnamese restaurants.
"One is married in good times as in bad," Guhle said. "I guess we started with the bad."
