We went to where the bridge had been . . . as birds still tethered by a thread, spanning desolation's arc dividing stress by what we said. One silent . . . while the other talked; self-moving bridges as we walked.
Two people walk to the spot where a bridge used to stand, and the poem quietly turns that gap into a picture of their relationship. The flood has taken the structure away, but the speaker keeps the idea of a bridge alive. What the speaker sees are "birds still tethered by a thread," a frail image of connection hanging on against all odds.
The final couplet carries the poem's real point. One person stays silent while the other talks, and as they walk, they become "self-moving bridges," each trying to cross the distance between them by their own effort. The poem suggests that words, or the lack of them, divide the stress rather than resolve it. The mood is wistful and tense, even a little sad. Nothing is shouted or settled; the ellipses leave pauses hanging in the air, much like the silence between the two walkers. It reads as a moment of closeness that's fraying, but not quite broken.