You could argue that both parties thrive on their opposition to the other. There is also a clear divide on policy. The Flemish nationalists are only prepared to enter a government with the Francophone socialists that delivers new state reforms, while such reforms are anathema to the Francophone socialists.
If the Flemish Christian democrats, liberals and greens all joined in, a coalition could be formed, but this would be one that doesn't possess a majority in Flanders. Such a majority isn't required by law. The Michel I government possessed no such majority in Wallonia. But in practise a federal government that doesn't have the backing of half of all MPs in the country's biggest community does seem a little unrealistic.
For this among other reasons people seized on the words of Elio Di Rupo when he suggested a federal government could be formed without a Flemish majority. It seemed to suggest Mr Di Rupo wanted to exclude the N-VA. In recent hours he has now been keen to clarify his words. Mr Di Rupo now says he was asked a question and was providing a simple answer. No more no less.
"This is a storm in a glass of water" he noted.