Mayor Bill de Blasio has at times teased his appointees about their diminutive statures, or in one case, an eye patch. But he had not, before Thursday, flirtatiously pinched a prominent official while announcing her new role. Or kissed her twice — on the lips — or given her a high-five.

If such behavior seems, at best, to lack a certain mayoral gravitas — at worst, to verge on riskier territory — it helps to know that the appointee in question was his wife, Chirlane McCray. Introducing her as “my best friend in the world, my closest confidante, my No. 1 adviser,” Mr. de Blasio announced at a news conference that he was naming Ms. McCray the chairwoman of the Mayor’s Fund to Advance New York City, a nonprofit entity that raises money privately to support a variety of city causes.

“This had to be someone who was as close to the core of what we’re all about as humanly possible, and I think we could safely say that no one could compete with Chirlane McCray on that particular score,” he said, with a laugh.

Ms. McCray sounded slightly overcome, and asked her husband to pinch her to prove that it was all real — the moment, his election and their shared elevation to positions of such influence.