The odd couple hit the studio together and tried to work on new material, but the union wasn't productive.
"It ended up being one of those 'don't meet your idol' moments," Adele tells Rolling Stone. "And the saddest thing was that I was such a big Blur fan growing up. But it was sad, and I regret hanging out with him.
"None of it was right. None of it suited my record. He said I was insecure, when I'm the least-insecure person I know. I was asking his opinion about my fears, about coming back with a child involved - because he has a child - and then he calls me insecure?"