Susan Hannah Macdowell Eakins (September 21, 1851-December 27, 1938) was an American painter and photographer. Susan married Thomas Eakins in 1884; she continued to paint but devoted much of her time to facilitating his career.
Biography on Wikipedia: https://en.wikipedia.org/wiki/Susan_Macdowell_Eakins

Portrait of Thomas Eakins by Susan Macdowell Eakins
c.1920-1925 / Oil on canvas / 50″x40″ / Philadelphia Museum of Art, PA

Susan Macdowell Eakins on Artnet: http://www.artnet.com/artists/susan-hannah-macdowell-eakins/

Further reading:
http://collection.terraamericanart.org/view/people/asitem/items$0040null:435/0
https://collections.dma.org/artwork/4174628
https://www.spellmangallery.com/artists/susan-macdowell-eakins