Ellen gets home from her tryst at 4.30. Those watching the clock know that she arrived at Banners restaurant at 12.30 and had to wait fifteen minutes before Hooper arrived. By the time they were ready to order it must have been close to one. The restaurant was practically empty and so their food came quickly. At a conservative estimate they had probably paid the bill and left by 1.30. How long would it take them to find a suitable motel where the walls weren't made of "Kleenex and spit"? Let's be generous and say thirty minutes. Then maybe another twenty minutes to register as husband and wife, and a few more minutes to "scout around". So by the time they're alone, it would be two thirty in the afternoon. Given that Ellen needs a minimum of twenty minutes to drive home, that gives the lovers about ninety minutes.
Ellen and Hooper's "coupling" is seen through Ellen's eyes, as a memory after the fact, and it's presented as a violent, atavistic act - described in the text as "an assault". Ellen falls asleep with images of Hooper's climax playing on a loop in her head, and is woken by her husband. Their conversation continues as Brody goes into the bathroom to relieve himself, and Ellen contemplates the capacity of the male bladder. And so the chapter ends with her husband holding his flaccid penis in his hand whilst Ellen's mind brims with images of another man's erection.
