On March 9th, 1879 he married a girl from Borre and (later) Bergen, Thorine (called Thora) Kathrine Torgersdatter Johnsen (1856-1937). They had five children together: Inga Katrine (1879-1958), Jørgine Marie (1883-1886), Karen Marie (1886-1900), Klara Johanne (1888-1966) and Thor (1893- ?). Knut also had one child, Katrine (born in 1874), by a girl in Kragerø, but the child died before she was a year old. In 1901 Knut and Thora divorced - in the late 1890's Thora and her children Inga, Klara, Karen (who died soon after) and Thor went back to live near her family in Bergen. Knut, now separated and apparently "fancy free", had two more daughters (in 1895 and 1904) by two different women in Kragerø...... Finally he was married again on Oct. 15th, 1904 to Maren Olsen (born 1864 on Langøy), a girl he must have known from his youth. She was now a widow with six young children. They settled on Langøy, near Knut's mother (more about her later), and had three children: Ingeborg Klara Marie (1904), Astrid (1907) and Anton Trygve (1909). Knut continued as a sailor, but made his last trip in 1911: he was steward on the barque Waaland returning from England to Norway with a cargo of coal in November that year, when the ship was caught in bad weather, capsized and sank. The whole crew was lost.
The photo (I think!) shows Knut and his first wife Thora late in 1882 or very early 1883. There were several photos of the Thorsens taken by the same photographer and with the same pose, so my guess is that the family had their photos taken before three of them left for the US in early February 1883.