She never married, however, and her most lasting romantic relationship was with the Renaissance Italian art expert Bernard Berenson. Berenson found Greene both charming and "miraculously responsive and most of all to the things I really care most about." The Bernard and Mary Berenson Papers in Harvard's Villa I Tatti, Florence, contains numerous letters by Greene. Although Greene may have burned all personal papers in her possession shortly before her death, her professional correspondence is archived in the collections of The Morgan Library & Museum.