One of the interesting through-lines in the history of female same-sex desire are the parallel strands of "attraction based on similarity" versus "attraction based on difference." If you will: femme-femme and butch-femme. (It would be interesting to look for historic antecedents for butch-butch attraction, which would also fall under the similarity model, but the primary examples tend to be femme-femme.) But these models of attraction or desire aren't limited to same-sex couples.