Melena married Frexspar, a preacher, against the wishes of her family. However, she's somewhat promiscuous and not faithful to her husband. The Wizard of Oz had a one-night-stand with her, having taken an elixir, which lead to the birth of Elphaba. Melena could not understand the child's green skin or sharp teeth; she also could not bring herself to love the child.
While raising the baby, Frexspar left on a long trip related to his preaching and a Quadling man named Turtle Heart visited her farm. She quickly began a sexual relationship with him, which she continued even after Frex got home (Frex wasn't aware of this at first, and Turtle Heart stayed in the guest room). Melena soon became pregnant by him with her second child, Nessarose.
It soon became apparent that Frexspar had also fallen in love with Turtle Heart, and so the three moved to Quadling Country. Turtle Heart was killed accidentally, however. Melena got pregnant again, by her husband for the first time, and gave birth to Shell, dying soon after. (Wicked: The Life and Times of the Wicked Witch of the West)