So, was Marcus... *MAJOR SPOILER*
Was Marcus actually real or just a figment of Olivia's imagination? The last scene, with the flowered wallpaper that looked so much like the flowers she brought to him in the hospital, made me think it was the latter.
Then again, they called her, "Mrs. Anderson," which made me think that she got out of the hospital after she left college, eventually married, and decades later ended up in a home when she was older.