Complex sentence: The term is now used most commonly to cover specifically gay male literature, with a separate genre of lesbian literature existing for women, although historically the term "gay literature" was sometimes used to cover both gay male and lesbian literatures.
Split into simpler sentences: The term is now used most commonly to cover specifically gay male literature with a separate genre of lesbian literature existing for women. Historically, the term "gay literature" was sometimes used to cover both gay male and lesbian literatures.