The unnamed man hired a crane in the central town of Ijsselstein to lower him over his girlfriend's house and into her garden for the surprise proposal early on Saturday morning, emergency services spokesman Jelle Mulder told AFP.
"The crane the man wanted to use to propose fell on a house. During the attempt to right it, the crane unfortunately slipped and fell on the house again," Mulder said.
Neighbouring houses have been evacuated and the huge crane is still on top of the house.
"We're looking at the best way to lift the crane without it falling again," said Mulder.
The would-be fiance jumped to safety and no one else was hurt, Mulder said.
"The people in the house the crane fell on are deeply shocked," he said.
The authorities will decide if the house needs to be demolished after the crane is lifted.
Despite the fiasco, the girlfriend accepted the marriage proposal, Dutch media reported, and the couple has now gone on holiday.
"They had a trip to Paris planned and the police told them that there was no reason to cancel," said Mulder. "I don't know if they've gone."
