Commentary Par XVIII 8

The word conforto, used as a noun to describe another human being (e.g., 'that person was my comfort'), has been employed three times before now ([Inf IV 18]; [Purg III 22], [Purg IX 43]), on each occasion assigned to Virgil; here, for the first (and last) time referring to anyone else, it obviously refers to Beatrice.  For the possibility that Dante is here reacting to Cino's 'Consolatoria' in response to the death of Beatrice, see Hollander (Holl.1992.2), p. 217: Cino's poem has Amor calling out for conforto on Dante's behalf.  Perhaps his text is responsible for Dante's referring to Beatrice here as he does.