In Book 14 of the Iliad, under the influence of a love potion administered by Hera, Zeus sweet talks at her, amorously mentioning seven other lovers he currently sees her as much more desirable than. The silver-tongued stud!
But his candor was limited – much went unmentioned. Bright-sky father, patron of hospitality, enforcer of oaths and honest business, King of Olympus and supreme ruler of the gods, although married to his sister Hera (goddess of marriage and monogamy), Zeus had many sexual dalliances: first with Niobe (Nioba, from southern Greece)), and later also with Aegina (Aigina), Alcmena (Alcmene, mother of Hercules), Antiope (perhaps by force, at any rate, as a satyr; resultant twins were exposed, i.e. left out to die), Calliope, Callisto (an Amazon from Arkadia in southern Greece, whom Zeus seduced while in the form of Artemis ), Cassiopea (from Crete), Dia, Demeter, Dione, Elara (or Elare, a princess from central Greece), Eurymedousa (a princess from northern Greece), Europa, Io (Hera’s priestess), Kalyke (Calyce, mother by him of Endymion, also from southern Greece), Themis, Thyia, Eurynome, Lamia (from north Africa), Laodemia (from Asia Minor, mother of Sharpedon), Leda (by whom, Helen of Troy and Polydeuces), Leto (mother of twins Apollo and Artemis), Mnemosyne, Hybris, Olympias (mother of Alexander the Great!), Persephone, Pandora, Phthia, Protogencia, Pyrrha, Danaë (mother of Perseus), Selene and Semele (producing Dionysus). Metis, the goddess of prudence, was Zeus’s first love; he swallowed her. When Zeus had an affair with his aunt Mnemosyne, he coupled with her for nine nights. This scenario produced nine daughters, who became known as the Muses.
Demeter, Alcmene, Semele, Io, Themis, Eurynome and Metis he married. He has sex with his daughter Aphrodite and thus produced Priapos, a deformed God who had the shape of a penis.
He fucked Goddesses Aix, Deino, his sister Demeter (by rape, which produced Persephone, whom he also raped, producing an elder Dionysus, whom the Titans killed – according to Orphic myth), Dione (mother of Aphrodite), Himalia, Hora, Callirhoe, Carme, Maia (mother of Hermes), Othreis, Plouto, Sinope, Thaleia, a nymph from Africa (unnamed), and his grandmother/great-grandmother Gaea (twice!), accidentally (!) impregnating her. It was Gaea who warned Zeus, in a replay of the main Cronus story, that a son would one day displace him. As his then-wife Metis was pregnant, he swallowed her, as his father Cronus had swallowed his elder siblings (Homer places Zeus as ‘first-born’). Swallowing his wife seems to have given him a headache; from his split-open head Athena then sprang (fully armed). Zeus then married Themis, a Titan, mother of the Seasons and Fates.
Zeus fell in love easily and had many affairs with various women, however he would severely punish anybody who attempted to escort/fall in love with his wife Hera – like the giant Porphyrion who took a lightning bolt from the enraged god for lusting after his wife (albeit with a little help from the love god Eros). He also had a boy called Ganymede, a Trojan prince, who was so beautiful that Zeus abducted him from his cradle by taking the form of an eagle.
Some Mythologists hole that stories of Zeus’ infidelities were inspired by tales of patriarchal institutions overpowering ancient matriarchies around the Mediterranean. While patriarchy insisted on an all-powerful father figure, matriarchal systems were comfortable with many autonomous local goddesses, who later became the nymphs and mortal princesses ravished by Zeus in Greek lore. The stories also indicate the rise of marriage as an institution in ancient Greek society, and the demand of women to tame the polygamous desires of men.
Allegory, amalgamation of older stories, meta-memory, instruction, amusement, and entertainment in the manner of pageantry, all were surely involved in the evolution of the tales.
Maybe the legends were just an early form of surrealism, like Coney Island style fun-house mirrors.