Elaineor The Lily Maid of Astolat Sophie Gengembre Anderson (1823-1903)

The picture has something of this: people, tree, man, two, mammal, recreation, outdoors, woman, reclining, water, side view, wear.
Perhaps it’s a painting of a man and a woman in a boat in the water with a dog on the side of the boat and a flag on the back.