We know very little about the inner workings of Andrew Marvell. Many poets in this difficult period kept to intimate, domestic topics, but Marvell was unusually self-enclosed. The successful MP seemed have no outward personality but stayed a quiet bachelor who loyally supported the Puritan cause. His political writings were masterly, but the now-celebrated lyrics were not published in his lifetime, nor even much circulated. Whatever the ruling faith - Romanticism, Symbolism, Modernism, etc.
Poetry is a fusion of the two faculties.
Many poets find the distinction unhelpful, since all realities invoked by language are marvellous, the mundane no less than the exotic. Marvell's extraordinary supra-sensitive poetry was only possible with strong stanza shaping, just as the period he looked wistfully back to required sensible government for contented private life.