Elaine May (born April 21, 1932) is an American screenwriter, film director, actress, and comedienne. She made her initial impact in the 1950s from her improvisational comedy routines with Mike Nichols, performing as Nichols and May. After her duo with Nichols ended, May subsequently developed a career as a director and screenwriter. Her screenwriting has been twice nominated for the Academy Award, for Heaven Can Wait (1978) and the Nichols-directed Primary Colors (1998).

Audiences were still discovering them in 1961, four years after they arrived. However, at the height of their fame, they decided to discontinue their act that year and took their careers in different directions: Nichols became a leading film director; May became primarily a screenwriter and playwright, with some acting and directing. Among the reasons they decided to call it quits was that keeping their act fresh was becoming more difficult. Nichols explains:  Several things happened. One was that I, more than Elaine, became more and more afraid of our improvisational material. She was always brave. We never wrote a skit, we just sort of outlined it: I'll try to make you, or we'll fight--whatever it was. We found ourselves doing the same material over and over, especially in our Broadway show. This took a great toll on Elaine.  Nichols said that for him personally the breakup was "cataclysmic", and he went into a state of depression: "I didn't know what I was or who I was." It was not until 1996, thirty-five years later, that they would work together again as a team, when she wrote the screenplay and he directed The Birdcage. It "was like coming home, like getting a piece of yourself back that you thought you'd lost," he said. He adds that May had been very important to him from the moment he first saw her, adding that for her "improv was innate," and few people have that gift.  Director Arthur Penn said of their sudden breakup, "They set the standard and then they had to move on." To New York talk show host Dick Cavett, "They were one of the comic meteors in the sky."  They reunited for benefits for George McGovern for President in 1972.

Using a quote from the above article, answer the following question: Who decided to call it quits?
They