because he was a player
Zeus had multiple human women lovers, but never had a wife. This made Hera mad, and is why she gave birth to Hephaestus.
Yes, Demeter and Zeus were lovers. They produced a daughter Persephone.
Zeus had scores of lovers.
they are lovers
Demeter's immortal lovers were Poseidon & Zeus, her mortal lovers were Jasion, Karmanorand Mekon.
Hera was his wife but Zeus had many lovers.
Hera defeated zeus lovers and she was mad of zeus
There are too many to name.
Possibly her jealousy. She was very jealous of Zeus' lovers and of his offspring from these lovers.
Zeus and Demeter were not lovers. Demeter bore a daughter by Zeus named Persephone (Kore), however Zeus married his other sister, Hera. (Note that Zeus mated with many other goddesses and mortals, not just his lover and Demeter)
Doris
she defeated many of Zeus's lovers