Always on the lookout for under-represented women, I have found Katharine Tynan in "The Irish Identity: Independence, History, and Literature" taught by Dr. Marc C. Conner, Washington and Lee University, The Great Courses Plus.
A prodigious writer, Tynan (23 January 1859 – 2 April 1931) penned more than 100 novels, five autobiographical volumes and several volumes of poetry, but is most frequently mentioned because of her substantial influence on William Butler Yeats.
"In sowing the seeds of the renaissance of Irish culture, Hyde, Russell, and Yeats were joined by another figure, the poet and novelist Katharine Tynan, a good friend of Yeats and a prolific author whose career spanned many decades. She was an important poet even before Yeats, having published two volumes of poems in the 1880s and more than a dozen books in the 1890s," Conner says.
Her poem 'Any Woman', expressed the centrality of the woman figure in Irish mythology."
"Tynan and Yeats met in 1885 and already she had formed a weekly evening gathering over literary conversational ideas, a sort of small literary salon of Dublin writers. She and Yeats soon became confidants and exchanged many letters over the years. As Yates emerged as a young poet, and then became a major poet...he would try his ideas out on Tynan, gauge her responses, and he formed many of his aesthetics of poetry through his correspondence with her," according to Conner. Wikipedia suggests that Yeats "may have proposed marriage and been rejected, around 1885."