Pennsylvania Ballet ballet mistress Kyra Nichols is leaving the company for a teaching position in another city and is taking with her husband David Gray -- the company's still relatively new executive director.

"My wife has been offered an amazing position," Gray said. "There are dozens of people who run dance companies, and the ballet will find a good one, but there's just one Kyra Nichols, and her talents are unique."

Gray said the school to which Nichols is going is not ready to announce her appointment, but his contract here required giving three months' notice before leaving, hence the timing.

He declined to specify the institution.

The chairman of the ballet's board of trustees, David Hoffman, said he was sorry the company was losing them but added: "I wish them well. People should take opportunities when they get them."

Hoffman said the company would form a search committee, hire a firm, and then cast its eye nationally for Gray's replacement. He said he hoped to have a new chief installed within six months. An interim director is likely.

"We are very happy with what's happening on the stage side," he said. "Now, we just have to keep bringing the organization into a state of health and continuity, and I am hoping we can find the right person. It's not going to be easy. There are a number of ballet companies across the country looking, but I think we have something exciting here."

Gray, 57, was named Pennsylvania Ballet's executive director in March 2015, after serving in an interim role for eight months. He plans to leave the post June 30.

He said that among the work of which he is most proud is the company's growth in community engagement programs and sensory-friendly performances for special-needs audiences. "We did a sensory-friendly Nutcracker and just did a Jungle Book, and we have classes at Broad Street Ministry and have classes for people with Parkinson's in our studios," he said. "There is so much we do that is not as visible [as the mainstage productions] that makes the cultural fabric of Philadelphia broader and more inclusive. If I have tear-producing moments, it's at those performances. That work is just extra-special."

Nichols, 58, retired from the New York City Ballet in 2007 after 33 years and was closely associated with the work of George Balanchine. As the Dr. Morris H. and Esther Kean Ballet Mistress at the Pennsylvania Ballet, she has worked on setting Balanchine works on the company.

Hoffman said he did not know the fate of that position -- when it would be filled or whether it would be taken by an artist in the Balanchine mold. Pennsylvania Ballet artistic director Angel Corella has deemphasized the importance of Balanchine as core to the company's identity since taking over in the 2014-15 season.

"It is preferential to have someone with Balanchine experience, but I don't know what we will find," Hoffman said. "We are probably going to add staff, but that position came as serendipity by her being David's wife and who she was."

The ballet mistress or master trains and coaches dancers, and helps bring the choreography to stage. The job is to some extent the dance equivalent to what a conductor does in rehearsal for the orchestra. Pennsylvania Ballet also employs ballet master Charles Askegard.

Pennsylvania Ballet leaders also will be seeking to hire a new director of the ballet's school in an open but still-uncompleted facility on North Broad Street. "The company is looking at how much more building we can do and what kind of school we can have before we hire someone," Hoffman said.