In the friendliest possible way, German Chancellor Angela Merkel made it clear this week that she and U.K. Prime Minister David Cameron have essentially incompatible views about the future of the European Union.

This wasn't much of a surprise: After all, the same goes for the country's respective electorates. The question is whether these incompatibilities can be tolerated, or whether they'll force a divorce.

Cameron has promised a referendum in 2017 on the U.K.'s membership in the EU — membership on new terms, he hopes, to be negotiated if he wins re-election next year. He has said he wants fundamental reforms that would move some of the powers previously granted to Brussels back to national governments. Merkel, addressing both houses of the U.K. parliament, offered no reason to think this will happen. "Some expect my speech to pave the way for a fundamental reform of the European architecture which will satisfy all kinds of alleged or actual British wishes. I am afraid they are in for a disappointment," she said.