"Even if relationships are destructive, people cling together," photographer Nan Goldin writes in the introduction to the 1996 edition of her seminal monograph The Ballad of Sexual Dependency, originally published in 1986. All the Beauty and the Bloodshed, the unflinching, Oscar-nominated documentary helmed by Laura Poitras, is also about a "struggle between autonomy and dependency" – one waged by Goldin …