For the lines
Pale grew thy cheek and and cold,
Colder thy kiss....
alliteration have been used. The technique is used for the letter sounds of k and c.
For the lines
The dew of the morning
Sunk chill on my brow—
It felt like the warning
Of what I feel now.
there is a regular rhyme scheme for the words brow-now and morning-warning. Additionally, the author applies foreshadowing to the lines.
The lines A shudder comes o'er me— indicates a metaphor how the main character feels towards his love.
Overall, the the lines focus on the language of sensory description of a physical intimacy.