I can't really blame Wolfsburg for not wanting to sell and making it as tough as possible. This is their selling Bale/Suarez moment. He is the sole reason they are in the champions league and he's won them 2 trophies in a year - and this is a club who's barely won anything ever.
They know that no matter what we pay, 45m, 50...70m they can't replace De Bruyne. The best they can do is buy a couple of players that might become as good as him one day.
That's why this is dragging out. They're probably hoping to convince KDB to stay.
But I very much doubt they will, so they'll cave in eventually. Might be in a day, might be in a week.