Although not called a goddess, Arthur's Queen, Guinevere is a bride queen archetype for Anglo-Saxons and Europeans. Here we see Guinevere performing that all important fertility goddess function, bringing in the spring on May Day.  A-Maying is an ancient Celtic tradition.
The month of May is named for an earth goddess, Maia, spelled like Gaia but with an M.  So Guinevere here is invoking the spring earth goddess. She no doubt represents an embodiment of that goddess, as her husband was a kind of sacred and dying king.

Every ethnic group seems to have Sacred Bride imagery. And a lot of the brides get tainted or lost.  In the original Arthurian legends of Britain, Guinevere is not a false lover who betrays Arthur by sleeping with Lancelot.  That part of the story was added much later. Like, by centuries. 

Guinevere A-Maying

Hon. John Collier