In her important book “Sexual Fluidity” Professor Lisa Diamond laments the mistaken assumption that lesbianism is fixed like male homosexuality and argues that this belief is the result of gay-normativity and male prejudice in gay research. She is hopeful that this has changed slightly in the last decade, revealing a picture of male and female sexual orientation as “distinct phenomena instead of two sides of the same coin.” It reveals that “one of the fundamental, defining features of female sexual orientation is its fluidity,” a “situation-dependent flexibility in women’s sexual responsiveness,” making it possible for women to desire either men or women under certain situations regardless of their generally identified “sexual orientation.” If this is true, it means lesbianism is not an orientation as we popularly understand the term today. Diamond concludes,

This is why a woman like Anne Heche can suddenly find herself falling madly in love with Ellen DeGeneres after an exclusively heterosexual past [and present], and why a longtime lesbian can experience her very first other-sex attractions in her forties.