Who is titania jealous of?

Titania, the Queen of the Fairies in Shakespeare's "A Midsummer Night's Dream," is jealous of the changeling boy that Oberon, her husband, wishes to take into his service. Her jealousy stems from Oberon's desire to possess the boy, leading to a conflict between the couple. This rivalry drives much of the play's plot, as Oberon seeks to manipulate Titania into relinquishing the child.