Loneliness is the subject here, and the poem shows how it feeds itself. The poem has no named speaker, and its subject is never "I" but the act of "living in isolation," which seems to do everything in the poem. It builds islands, watches shadows blur together in water, hopes for reunion, and in the end looks away and weaves a lie.
The images are quiet and a little sad. Shadows melding in water suggest closeness that isn't real, only a reflection of people merging. Hopes revive "when stars fall," which hints at wishing on shooting stars, a last-resort kind of hope. Then the tide arrives, a sign of something bigger and unstoppable, and the isolated figure simply closes their eyes.
The mood is wistful and resigned. The speaker seems to know the reunion probably won't happen, yet chooses comfort over truth. The title makes this clear: the "new lie" is a story told to survive solitude, and the word "new" suggests it won't be the first.