But in the last verse he tells us that the angel is always there, nevertheless, even when the good woman becomes old.

The angel is the Mother-soul.
Wordsworth's idea that character is the supreme charm was expressed very long before him by other English poets, notably by Thomas Carew.
He that loves a rosy cheek, Or a coral lip admires, Or from star-like eyes doth seek Fuel to maintain his fires: As old Time makes these decay, So his flames must waste away.
But a smooth and steadfast mind, Gentle thoughts and calm desires, Hearts with equal love combined, Kindle never-dying fires.
Where these, are not, I despise Lovely cheeks or lips or eyes.
For about three hundred years in English literature it was the fashion--a fashion borrowed from the Latin poets--to speak of love as a fire or flame, and you must understand the image in these verses in that signification.

To-day the fashion is not quite dead, but very few poets now follow it.
Byron himself, with all his passion and his affected scorn of ethical convention, could and did, when he pleased, draw beautiful portraits of moral as well as physical attraction.

These stanzas are famous; they paint for us a person with equal attraction of body and mind.
She walks in beauty, like the night Of cloudless climes and starry skies; And all that's best of dark and bright Meet in her aspect and her eyes: Thus mellow'd to that tender light Which heaven to gaudy day denies.
One shade the more, one ray the less, Had half impair'd the nameless grace Which waves in every raven tress, Or softly lightens o'er her face; Where thoughts serenely sweet express How pure, how dear their dwelling-place.
And on that cheek, and o'er that brow, So soft, so calm, yet eloquent, The smiles that win, the tints that glow, But tell of days in goodness spent, A mind at peace with all below, A heart whose love is innocent! It is worth noticing that in each of the last three poems, the physical beauty described is that of dark eyes and hair.

This may serve to remind you that there are two distinct types, opposite types, of beauty celebrated by English poets; and the next poem which I am going to quote, the beautiful "Ruth" of Thomas Hood, also describes a dark woman.
She stood breast-high amid the corn, Clasp'd by the golden light of morn, Like the sweetheart of the sun, Who many a glowing kiss had won.
On her cheek an autumn flush, Deeply ripen'd;--such a blush In the midst of brown was born, Like red poppies grown with corn.
Round her eyes her tresses fell, Which were blackest none could tell, But long lashes veil'd a light, That had else been all too bright.
And her hat, with shady brim, Made her tressy forehead dim; Thus she stood among the stooks, Praising God with sweetest looks:-- Sure, I said, Heav'n did not mean, Where I reap thou shouldst but glean, Lay thy sheaf adown and come, Share my harvest and my home.
We might call this the ideal of a peasant girl whose poverty appeals to the sympathy of all who behold her.