Devibhagavatapurana 3.30.5

3.30.5

upaviṣṭaṃ tadā rāmaṃ sānujaṃ duḥkhamānasam |
papraccha nāradaḥ prītyā kuśalaṃ munisattamaḥ ||

On Râmachandra taking his seat there with Laksmana with a grievous heart, Nârada asked him in a sweet tone “O Descendant of Raghu! Why are you being afflicted with sorrows like an ordinary mortal? I know that the evil minded Râvana has stolen Sîtâ Devî. I heard while in the heavens that Râvana, the descendant of Pulastya, stole away Jânakî, out of fascination, could not know that would be the cause of his death. O Descendant in the family of Kâkutstha! It is for the killing of Râvana that your birth has taken place; and for that purpose Jânakî has been stolen now.
Note:-- The real Jânakî was not stolen; Her shadow form was stolen.