The Countess of Lathom John Singer Sargent (1856-1925)

The picture has something of this: people, woman, wear, dancing, two, position, veil, furniture, dress, indoors, music, performance, dancer, portrait, baroque, ballet dancer.
Perhaps it’s a painting of a woman sitting in a chair wearing a black dress with a white sash around her neck and holding a glass of wine in her hand.