What techniques does Fitzgerald use to introduce tension between Tom and Daisy?
Tom and Daisy Buchanan are introduced in such a way as to emphasise their elite status in society, both individually and as a married couple. They both come from wealthy, established families, and on the surface, they appear to be well matched. The perceptive narrator notes, however that they “drifted here and there unrestfully” (Fitzgerald, 2001, p. 6), ultimately remaining unsatisfied with their marriage, despite a year-long visit to France, and frequent outings for tennis, golf, jazz, and other expensive pursuits. This evident tension in their lives is further increased by Tom’s frequent infidelities and Daisy’s obvious attraction to Gatsby. The theme of adulterous love highlights the inherent instability that comes with a marriage of convenience, since it is designed mainly to preserve the social status of the two individuals, and does not represent a loving union.
Another layer of tension between Tom and Daisy can be seen in the way that Tom is demonised, and Daisy is idolised, at least in the first half of the book. Tom is described negatively as “a brute, a great, big hulking specimen” (Fitzgerald, 2001, p. 10) by Daisy. He is labelled “the polo player” (p. 67), by Gatsby, presumably in a dismissive way, highlighting Tom’s lack of intellectual sophistication. Daisy and her daughter Jordan, however, are depicted positively, as “silver idols weighing down their own white dresses” (Fitzgerald, 2001, p. 73). Tom’s sexual promiscuity is contrasted with what Gatsby perceives as Daisy’s innocence and purity. The reader may see things rather differently, especially as Daisy’s callousness is revealed towards the end of the book, but for most of the narrative, the author creates tension through this polarisation in the way the two Buchanan characters are described.
Fitzgerald, F. S. (2001)  The Great Gatsby. London: Wordsworth editions.