Definitely a scorned lover! Murder, dragons, kings and princesses… this is a good one.
Medea is an enchantress in Greek mythology. She was the daughter of King of Colchis. She fell in love with Jason and enabled him to slay the sleepless dragon that guarded the golden fleece (I imagine this is today’s equivalent of letting a man kill a spider in your bedroom “Oh you’re SO brave!”). The two were married, and went to Greece and helped King Peleus regain his youth suggesting he bathe in Medea’s magic cauldron. But the cauldron boiled him alive, a trick to help Jason claim the throne.
However, Jason grew tired of Medea, and began to pursue Glauce. Medea befriended the young princess and sent her a dress that killed her instantly. Medea also murdered her own children and then fled to Athens in a chariot led by dragons!
Don’t mess with the dress.
There is a full article on the stories of Medea and various interpretations here: