Robert Frost's poem, "Desert Places," is constructed with four stanzas of four lines, each line written in iambic pentameter (rhymed lines of ten syllables with the even-numbered syllable bearing the accents). The main theme for the poem seems to be that of loneliness and not sense of belonging; however, if one were to identify a sense of belonging in the poem it would probably have to be from what isn't said directly. For example, he declares that he isn't afraid of any void, like that in space where no human exists. The implied notion behind this is that we don't belong in space, but in fact, here on earth.
Another thought that brings out a sense of belonging is in the line that reads, "The loneliness includes me unawares," suggesting too that he "belongs" or feels comfortable in a state of solitude, so much in fact that he didn't even know he was lonely until the actually thought about it.