CAMBRIDGE, Mass. — A Harvard faculty member who decided to represent Harvey Weinstein at his rape trial is losing his position as head of a student house at the college. Harvard College Dean Rakesh Khurana said in a written statement Saturday he would not renew the appointments of Ronald Sullivan and his wife, Stephanie Robinson, the school’s first Black faculty deans, citing concerns about the climate at Winthrop House, which he described as serious. Sullivan lives at the house and supervises students there. Some students and faculty members have faulted Sullivan’s decision to represent Weinstein and his response to students’ concerns. Khurana called the situation regrettable and said efforts to improve the climate were ineffective. The couple said in an email they were surprised and dismayed. They said Harvard unilaterally ended discussions that had been progressing.