"A Red, Red Rose" is about the power of love over the inevitable passage of time. The speaker stresses his adoration for the object of his desire as he takes leave of her (the reader is never told why he must go). He compares his love to a newly bloomed rose in the summertime and a beautiful melody, suggesting a youthful passion motivated by the speaker's beauty and charm. He claims he will love her as long as there is life and until the seas go dry and the rocks melt in the sun.

It has been suggested that the speaker's overzealous protestations of love hide an insincere motive, that perhaps the speaker has seduced the beloved and is leaving her with no intention of returning. The choice of imagery to stress that this point validates this idea: after all, roses fade and even the most beautiful music eventually ends. Even the beloved's fairness so praised by the speaker is doomed to end once she begins to age. Thus, one could argue the poem's theme is ironic: it is about the briefness of passion rather than eternal love.

However, it is possible to argue that the speaker is sincere and that his love truly will last as long as he claims. Regardless of how any individual reader interprets the poem, there is no doubt that the chief theme is how love is affected (or not affected) by time.

In “A Red, Red Rose,” the speaker wishes to emphasize not just the love he has for his beloved, but the strength of that love and its power to endure in the most trying of circumstances. The speaker is so deeply in love with his “bonnie lass”—or beautiful young woman—that he pledges his love to her from now until the seas run dry. Such hyperbole is the stuff of both love poems and love songs but is no less earnest for that. At the same time, we may wonder why the speaker feels the need to affirm his love in such hyperbolic terms. One gets the impression that he’s protesting just a tad too much.

In any case, whatever the speaker’s true feelings, one cannot help but admire his tenacity in expressing the strength of his feelings. He states that he will love his bonnie lass until the rocks melt with the sun. More realistically, and less hyperbolically, he affirms his commitment to love his beloved while the sands of life still run.

In the final stanza, the speaker takes his leave of his beloved, but, in one last illustration of the strength of his love, pledges that he will one day return to her, even if they should be ten thousand miles apart. Such is the power of love.

While the overriding theme is Love in Robert Burns's "A Red, Red Rose," there is another theme suggested even in the title: Time.

A rose that is very red is at its fullest and will shortly die. The first two lines suggest the temporal nature of love:

O my Luve’s like a red, red rose,
That’s newly sprung in June: 

However, Burns makes a distinction in his verses: When the "Luve" is a person in this poem, the life is limited, just as is that of a rose; however, whenever "Luve" is mentioned relative to emotions, there are images in the poem suggesting that time is unable to affect the life of the love:

Till a’ the seas gang dry, my Dear,
And the rocks melt wi’ the sun:
O I will luve thee still, my Dear,
While the sands o’ life shall run.

Because of this distinction in the meaning of the speaker's declaration of his love, the emotion and life of this love is afforded more depth and intensity. And, thus, the last lines suggest both the temporality and the eternity of love. Clearly, Robert Burns's poem strives to find a compromise between the temporary and the eternal nature of love.

The theme of this poem is love. The poet compares his lover to a red, red rose. A red, red rose is one in full bloom. 

The poet tells his lover she is beautiful: "fair art thou."

He then says he will remain loyal to her forever. He repeats twice that he will love her until " the seas gang dry." This means he will love her until the seas dry up. He also says he will love her until the rocks of the earth melt, and until time itself runs out. In the last stanza he is saying goodbye to her before they separate, but says he will love her through all eternity.

Thus, the theme of this poem is about more than love: it is about a love that will never die. But, in fact, it is about a poet saying his love will never die. The exaggerated metaphors he uses, such as loving her until the seas dry up, contrast with her being a rose in fullest bloom. Will he love her as much, the poem asks, when her bloom has faded, as it soon will, and she is no longer beautiful? So the poet makes great claims about undying love but by using so much exaggeration, the poem also raises questions about whether the poet's love really will last or whether he just thinks it will.