The speaker watches his wife withdraw into a space of her own, and in doing so she seems to find a "new now," a fresh way of being present. He admits he knows nothing about it. Left on the outside, he turns to his own habits: writing in his "book of dark weather" and performing a "mad dance." Both images suggest a restless, anxious attempt to work through his feelings, noisy and a little frantic.
The last stanza sets her against him. Her way is "the best, most natural," and she "keeps time" rather than waving a "rash flag." Where he flails, she is steady, measured and unshowy. The mood is quiet and uncertain, mixing admiration with a hint of bewilderment and self-mockery. The speaker doesn't resent her calm so much as recognize it as wiser than his own response. The poem leaves open what exactly she is retreating from, but the contrast between her patience and his agitation is clear.