A celebration of novelist Christopher Isherwood and painter Don Bachardy looks back at their 33-year relationship. The exhibition, touching on Isherwood’s years in Berlin, features original art by Bachardy (portraits and nudes), film and photographs of the couple, audio stations playing their love letters as read by Simon Callow and Alan Cumming, and works by David Hockney, including a 1976 lithograph from the artist’s private collection as well as a 2018 drawing of Bachardy, never before exhibited in Europe. —J.V.