The title "Breakup" works two ways at once. It's the cracking of winter ice, and it's the end of a relationship. The poem lets both meanings sit together, so the thaw of the season and the splitting of two people feel like one event.
The first lines make that link directly: "breaking up / the frost on our common hurt." Something shared and frozen is being broken apart. The speaker seems to be at the moment of separation, when a final word, "go," is said or heard. That word pushes "against new leather," which suggests something stiff and unfamiliar, like a new boot that hasn't yet been worn in. Judging by the imagery, leaving feels awkward and uncomfortable.
The last image is the strangest and warmest: a foot "cowled" in rabbit fur. It could point to comfort, or to a small, soft protection against the cold that remains. The mood is quiet, wintry and restrained, with pain handled in a few cool, exact images rather than open emotion.