The speaker begins by noticing that everyone else wears a wedding ring on the fourth finger of the left hand, while their own finger is bare. Instead of treating that emptiness as a lack, they move toward another person, and the two of them seem to take up the whole world. Their home isn't a house but bedrock below and a red, molten, volcanic sky above, which makes the love feel huge, raw, and a little dangerous.
In the second half, the idea of a ring changes. It is no longer a piece of metal but something made from the body: the speaker's arms circle the other person's belly, and the two of them form the ring together. The belly might hint at pregnancy, though the poem never says so outright. The ring then widens into air, fire, earth, and water, the basic elements, wrapping around the couple. The mood is warm, defiant, and elemental. The repeated "around us" at the end feels like a quiet, steady embrace.