Summary
The speaker finally parts with his lover. He tells her goodbye, calling her the "best," "fairest," "first," and "dearest." He wishes her well, hoping that she experiences joy and love in her new life. Then, closing out the poem, he actually repeats its first four lines, in which he repeats the words "ae fond kiss," and explains that he'll pledge himself with tears, groans, and sighs.
Analysis
Here, Burns pulls out all the stops. Three lines in this stanza end with exclamation points, showing the finality and intensity of the lovers' parting. At the same time, the speaker exercises an odd restraint, finishing his speech with the same four lines that began it. It's as if he wants to keep talking to the poem's subject until the moment of his departure, but can't think of anything new to say—after all, a permanent goodbye isn't the ideal time to start a new conversation. Furthermore, by ending the poem in the same place that it began, Burns demonstrates that all the speaker's talking isn't actually enough to change his situation. Even after sharing his tortured feelings, he's in the same place he was before, forced to say goodbye. This repetition has one other effect too—it creates a kind of chorus or refrain, making the poem feel catchy, like a song. Burns was interested in songs as well as written poetry, and his commitment to writing something memorable and songlike comes through clearly in these final lines.
In this final stanza, consisting of eight couplets, we can see a clear split between the focus of the first two couplets and that of the second two—namely, the first two center around the lover and the speaker's hopes for her, while the second two center around the speaker's hopelessness for himself. In the first four lines of the stanza, he repeats the phrase "fare the well," listing the positive experiences that he wants his lover to enjoy. This half of the stanza, as a result, is studded with pleasant-sounding words: love, treasure, joy. Yet these words are broad abstractions, as if the speaker himself is too far away from these experiences to truly wrap his head around them.
The closing lines, however, return to some of the most vivid sensory images of the poem. These include the specificity of the action "kiss," as well as the aural images "heart-wrung tears" and "warring sighs." Thus, Burns doesn't just create a contrast between the lover's hoped-for joy and the speaker's dreaded misery. He amplifies that contrast, showing how immediate the misery is, while the joy is nothing but a faraway idea approaching platitude.