The goddess who was Zeus’s wife and strongly opposed the Trojans was Hera. In Greek mythology, Hera is both Zeus’s sister and wife, queen of the gods, and goddess of marriage. In the Iliad, she sides with the Achaeans and repeatedly works against the Trojan army.
Her hostility toward Troy began with the Judgment of Paris. Paris, a Trojan prince, awarded the golden apple to Aphrodite instead of Hera after the goddesses offered competing rewards. Hera’s anger at this decision becomes part of the mythic explanation for her support of the Greek expedition against Troy. She also resents the Trojan cause because Aphrodite’s promise helped Paris obtain Helen.
Hera’s opposition is active rather than symbolic. She encourages the Achaeans, attempts to influence Zeus, and helps create opportunities for the Greeks to regain ground. In the famous Deception of Zeus episode in Book 14, she distracts Zeus so the fighting gods can assist the Achaeans. Demeter, Artemis, and Aphrodite are not the canonical answer: Artemis and Aphrodite support Troy, while Demeter is not a principal partisan in the Iliad’s war narrative.