Green, Monica H. 1990. “Female Sexuality in the Medieval West” in Trends in History 4:127-58..
This is a long summary article on ideas, attitudes, social structures, and legal principles relating to women’s sexuality in medieval Europe. Only a very small section is at all relevant to same-sex sexuality, and that is in a section entitled “Continued Silences” so you can already guess how scanty it’s likely to be, especially given that the “silence” it refers to is women’s own writings about sexuality in general, not specifically same-sex experiences. (It’s always useful to take note of the publication date of articles like this. There has been an explosion of interest and new research in same-sex history since 1990.)
Green notes that the genres of data most useful for women’s sexual attitudes in more recent centuries are lacking for the medieval period: diaries, newspapers, personal correspondence, and female-authored literary works. (Lacking, but not entirely absent.)
The evidence that does exist on women’s same-sex behavior has been subject to conflicting interpretations. The scarcity of references to female homoeroticism in medieval medical literature (as by William of Saliceto) could indicate that doctors didn’t take it seriously...or that it was discussed only when considered a medical (rather than a behavioral) issue. The references to women’s homoerotic activity in penitential manuals suggests an awareness of the practice...or at least offical concern about it. But differential attitudes toward various practices suggest that it wasn’t the same-sex aspect that was concerning so much as gender transgression in its performance, as with the use of artificial penises.
Women’s own voices are frustratingly rare on the topic. In other contexts, as in the lives of female saints, there is evidence that the dominant male attitudes about women’s lives may have had very little in common with how women viewed their own lives. The fundamental asymmetries between men’s and women’s concerns may mean that male preoccupations with sex have been erroneously assumed to be relevant for women as well. Looking at the writings that we do have from women, female religious writings are far less concerned with lust than male writers attribute to them. (That is, medieval men believed that women were just as preoccupied with sex as they were, but the women’s own writings don’t bear that out.)
Green concludes with the question of whether historians have been coming at this question from the wrong angle and have been constructing a history of how female sexuality was viewed by men, rather than a history of how sexuality was experienced by women.