Rocks, seas, sand, roses—there's plenty of nature in "A Red, Red Rose." It almost seems as if the speaker can't describe his love without mentioning some part of the natural world (the seas, rocks, roses, the seasons), which suggests that human emotions are organic, that they are just as natural as rocks and flowers. Yet even though emotions are natural, they appear to possess a longer shelf life than the stuff of the great outdoors. When the seas go dry and the rocks melt, the speaker says, his love will still be chugging along.
Human emotions are nothing like the natural world. Flowers die. Love doesn't. Geez, get it right, Burns.
All this nature stuff is nothing but mumbo jumbo. Their love can't last longer than the sea, because they'll die. Bummer.