When people started to talk openly about lesbian couples, they sold the image that this couple was formed by women who lived heterosexual roles. This stereotype determines that in a lesbian couple there “must be” a dominant side and a dominated side. This idea is deeply inculcated and assumed in society.
People assume roles based on participation from each woman in the housework or in interests of each of them regarding hobbies and preferences. For example, my ex-girlfriend’s friends told her that I followed the male role in the relationship for various behaviors I had; while my friends used to tell me that she followed the male role in our relationship for the same reason.