Five lines, one sentence, and a joke that only lands once you slow down. Frost gives us two people whom "they" have left alone. "They" are never named. The two respond not with hurt but with an experiment: they sit in a roadside hollow and "try if we cannot feel forsaken." That word "try" carries the poem. You only try to feel something when it isn't arriving by itself. Neglect ought to sting, but here it is so comfortable that the speakers have to act out the misery they assume they are owed.
The cause of the neglect sits in the second line. The others leave the pair alone "as two in whom they were proved mistaken." We are never told what they were wrong about. Judging by the phrase "the way we took," the pair chose a path others doubted, and events have gone against the doubters. So the withdrawal is a little sheepish, the way people go quiet after a prediction fails. The poem's strength is that it leaves this gap open. The two are vindicated yet ignored, and the poem is about what they do with that odd position. They might be a couple, since "two" and "us" suggest it, but the text doesn't say.
The sound of the poem works against any sadness. The rhyme scheme runs ABAAB, and the A rhymes are "took," "nook" and "look," short, rounded words that feel snug, like a hollow in a hedge. The two B rhymes, "mistaken" and "forsaken," are heavier and more formal, and they bracket the poem's idea. One is the verdict others reached about the pair. The other is the feeling the pair cannot quite produce. The final rhyme closes on exactly the emotion the poem declines to deliver. The rhythm helps. Each line has roughly four beats and a bouncing, tripping movement, and "With mischievous, vagrant, seraphic look" tumbles forward almost like a nursery rhyme. A lilt like that doesn't suit real desolation.
The imagery is small and exact. A "wayside nook" is off the road but still beside it. The pair haven't left the world, only stepped to its edge, where they can watch the others pass. The echo between "the way we took" and "wayside" reinforces this: they have left the main route without losing sight of it. Then comes the best moment, the three adjectives piled onto "look." "Mischievous" suggests a child up to something. "Vagrant" suggests a wanderer with no fixed place in society. "Seraphic" suggests an angel. Together they make a ragamuffin with a halo. Because the noun arrives last, after all that build-up, we picture the face before we understand its role. It is the evidence that the experiment will fail, since no one wearing that look can feel forsaken. "Seraphic" and "forsaken" also carry a religious sound, which I take to be deliberate, though the poem doesn't spell it out. It makes the pair's exile mock-solemn, a fall from grace that they are enjoying.
The small word "sometimes" matters too. Sitting in the nook and testing for loneliness is an occasional habit, a game they return to, like pressing a bruise to see if it still hurts. The poem never says whether they succeed. The phrase "if we cannot" reads like a challenge, and everything in the tone tells us how it will end.
Frost is an American poet often associated with plain speech and understated irony, and this poem shows both qualities in miniature. Roads and chosen paths turn up again and again in his work, but here the interest lies in what happens after the choice, when the watching crowd drifts away. The poem suggests that being unobserved can be a kind of freedom, and that self-pity is something you can pick up and put down at will. It leaves us smiling, but also asking how much of what we call loneliness is a part we sometimes step into because we think it is expected.