[Line 1] Late came the God. The unnamed pagan god is presumably the Greek Eros, son of Aphrodite, the goddess of love (known to the Romans as Cupido, and Venus). His unregarded forerunners refer to the earlier, unsuccessful attempts by Cupid’s minions to make the woman fall deeply in love.
[Line 3] The contempt be rewarded. She has incurred the anger of Eros, since the gods, as everyone knows, resent cocksure self-confidence.
[Lines 5 and 6] He poisoned the blade and struck home etc. I cannot help feeling that, when he wrote these lines, Kipling must have had in mind Bernini’s famous Baroque sculpture representing The Ecstasy of St Teresa, which shows an angel in the act of piercing the saint’s bosom with a fearsome javelin.
[Line 7] He made treaty with Time to stand still. So that time would not heal her wound.
[Line 9] midnights unslaked for her. To slake is to satisfy or quench one’s desire or thirst. Her midnight desire for the man she loved would not be slaked.
[Line 10] Till the stones of the streets of her Hells and her Paradise ached for her. A difficult line, until one realises how closely the poem is based on the story, in which, remembering the time when Harry was still in love with her, Mrs Ashcroft says that "’E was me master, an’—O God, help us!—we’d laugh over it walkin’ together after dark in them paved streets, an me corns fair wrenching in me boots!" (Page 123, lines 1-2) Also that, looking for him to come back after he had left her, "Goin’ over the streets we’d used, I thought de very pave-stones ’ud shruck out (would shriek out) under me feet." (ibid., lines 29-30) So the same streets have been her Paradise and her Hell, and her pain is so intense that she imagines it imparts itself to the stones. The God to whom she appeals for help, in what may only be a commonplace exclamation, may also be the God of the poem.