Egypt’s former foreign minister, Nabil Fahmy, who also served as his country’s ambassador to the United States from 1999 until 2008, once quipped that the U.S.-Egyptian relationship was like a “mature marriage.” This was during a particularly troublesome moment when the George W. Bush administration was squabbling with then-President Hosni Mubarak over political reform. The bickering between Washington and Cairo was hard not to notice at times, but there was no breakup. Alliances are, like a lot of successful marriages, hard work. Even the best of them go through periods of tension. The “special relationship” between the U.S. and the United Kingdom has often seemed less than that, for instance. The French can be so infuriating that former President Bill Clinton reportedly dreaded dealing with his then-counterpart, Jacques Chirac. It sometimes seems that the prime directive of Canada’s foreign policy is to portray itself as the anti-America — righteous in the world, in contrast to t...