Wordsworth's poem is a quiet appreciation of the the woman who often goes invisible. It has all the comparisons to nature a romantic poem naturally has. Compare the line, "fair as a star when only one is shinning in the sky" to Shakespeare's, "Shall I compare thee to a summer's day, thou art more lovely." While Shakespeare lifts his love's beauty above nature's best, Wordsworth's beauty is given a sort of "backhanded compliment." Sure, you can be fair as a star, but only if there is only one to compare you to/no one to overshadow you. He's not claiming she can outshine stars/nature, but that her beauty is more understated.
Considered part of Wordsworth's "Lucy" poems series, it is considered a meditation on loneliness and isolation--an appreciation of someone no one else sees except the poet himself, who admires her from afar.
She Dwelt among the Untrodden Ways
She dwelt among the untrodden ways
Beside the springs of Dove,
A Maid whom there were none to praise
And very few to love:
A violet by a mossy stone
Half hidden from the eye!
—Fair as a star, when only one
Is shining in the sky.
She lived unknown, and few could know
When Lucy ceased to be;
But she is in her grave, and, oh,
The difference to me!