The narrator uses juxtapostion (a smile being'the deadest thing') to show the incompatibility of the lovers.
'Keen lessons that love deceives/ And wring with wrong, have shaped me/ Your face'
Alliteration in 'wring with wrong' and assonance in the line 'keen lessons that love deceives' creates a bitter sneering tone, reflecting the narrator's bitterness towards his past relationship.
