How does the author use foreshadowing in Word of Honor?

In Chapter Eight, Tyson learns that David is being harassed for two reasons. One is the publicity around Tyson because of the book. The second is that Marcy was photographed in 1968, nude, at a fountain with a group of other nude students protesting the war. The media had discovered the photo and brought it to light after the publicity surrounding Tyson grew. The photo had made the cover of "Life," and journalists now were citing the fact that Marcy had been protesting the war while Tyson was fighting it. Tyson says that David should be taken away from the area as soon as school is out. Marcy has already suggested they put their home up for sale and other courses of action. One evening, Marcy returns from a late-night grocery shopping trip and she and Tyson have rough sex on the kitchen counter. It seems to be a normal occurrence for the two but this time Marcy feels that the situation was a foreshadowing of the bad times they're soon to endure.