The speaker describes a relationship built on restraint and surrender. They are tied up, physically "yours," and the partner wants more than the body: the "great blooming welts" suggest marks that point toward a love that claims everything. Yet the mood is not grim. The partner's hands are "coffeehot" and soothing, and the speaker feels cared for, given "everything I need."
The central surprise is a kind of exchange. The partner hands over their "darkest" side, and the speaker is proud, almost amazed, to take it in and turn it into "starbursts." Where there was once a "gnawing blankness," there is now something lively, even if the image of "joyous worms entwined" is a little strange and earthy. The view outside shifts too, filled with night-blooming flowers, and the two make "grand plans."
The ending keeps the tension alive. The speaker still strains at the cords, but it reads less like escape and more like eager participation, a willing surrender that feels intense, trusting, and transformative.