Who is Rudolf Margolius from Under a Cruel Star: A Life in Prague 1941-1968 and what is their importance?

Rudolf Margolius was the first husband of the author of the book. Margolius and Kovály married in 1945 after being reunited. Their prior relationship is not fully explained in the book, but was obviously romantic.They had one child—Ivan Margolius—together. Margolius is portrayed in the book as a devoted but often absent husband and father.