I wonder if Ben is the artist behind the paintings (we've already seen his penchant for art through the piano playing and appreciation of literature), that it isn't some sort of obsession to keep painting the same basic image over and over. I'm reminded of the movie "White Oleander" (which has really no connection whatsoever...but) where Astrid drew and re-drew the face of a woman she knew was important from her past but couldn't remember where she knew her from (turns out it was a very important element of her life). Regardless of who the painting is of (many theories such as Annie or Ben's mother), it just makes me wonder if Ben is the artist, repainting various versions of the same woman for some sort of catharsis.