American soprano Maria Ewing is seeking a divorce from opera and theater director Sir Peter Hall, departing director of Britain's National Theater, because of his "unreasonable behavior," Ewing's lawyer told Reuters on Wednesday. The pair worked together in Los Angeles for Music Center Opera's 1986 production of Richard Strauss' opera "Salome" and collaborated on numerous other operatic productions. The two met in 1980 when Hall directed Ewing in Mozart's "Cosi fan Tutte" at the Glyndebourne Opera. Lawyer Anthony Rubinstein said: "Lady Hall will be petitioning for divorce from Sir Peter on grounds of unreasonable behavior as soon as possible." Ewing and Hall are still expected to participate in the Music Center Opera's production of "Cosi" set to open Oct. 8.