Police said the 45-year-old man, who had allegedly tried to kill his spouse in the early hours of Thursday, had been known to them already.
The 45-year-old died of his injuries, while his wife was flown from the scene – a home for migrants in the town of Rüdesheim, Hesse – by police helicopter.
Two other people were also injured and taken to hospital.
Police said they were looking into the circumstances of the dispute, which were thought to be due to a relationship problem, and were seeking witnesses to the incident. The couple were said to be living apart.
There was no indication from authorities as to the nationality of the man or woman.
Germany took in around one million asylum seekers last year and expects about 300,000 arrivals this year. A large proportion of the migrants have come from war-torn nations such as Syria, Afghanistan and Iraq.
The influx has forced Germany to house newcomers in hostels, sports halls and army barracks, where cramped conditions have at times sparked conflict.