Are you asleep? Sophie throws her coat over the back of the armchair, puts her shoes beside the bed and goes into the bathroom. Through an open door Höller watches as she undresses, tying her hair up with a ribbon and stepping into the shower. He sees white skin as if through a film of fog: outlines only, never her entire body. Under the covers he begins to rub his penis. Timidly at first, then harder, but the ridiculous piece of meat between his legs will not grow erect. Despite the great arousal; certainly a reaction to the painkillers, thinks Höller.Höller is dying of cancer - hence the painkillers - and in a fit of moribundity decides to essentially throw over his business and spend the money staging a performance of Wanderer Fantasy. Sophie, his wife, doesn't know that he has cancer; she only knows that her husband is acting strangely, blowing the family's money on trifles, and threatening her promising legal career.
Naturally, their relationship has suffered a bit.
The line refers to Höller's "great arousal," but this is difficult to believe. He essentially seems to have apathy for everything except Schubert. In this moment it's more like Höller is trying to remember something he used to care about (sex, not Sophie). Hence the penis.
