There was just so much to worry about, these days. Honestly Bill was not sure he even wanted Fleur in Diagon Alley--at least here at Gringotts he was close by, and could be there in a moment if something went awry. But down the street at Madame Malkin's, near though it was, she could be swept away to the Ministry before he even knew anything was wrong.
Still, he knew Alberta was a friend of the Delacours, and he doubted she would let anything happen to Fleur without raising a fuss. And they could use the money, if they were to lose her salary from Gringotts.
"I have an idea, if you're willing to lie a bit. It would explain you leaving early today, and quitting too, and I doubt it would raise too many red flags even with the new eyes on the place."