She says she loves me?

My girlfriend says she loves me and that she needs me and that she see's me as nothing but a boyfriend but she says she wants to be friends. I dont get it i meen how can she love me and do this? She says the only reason why she hasnt left me is becuz she dont want to loose her best frie d and when i told her that she didnt have to be with me if she didnt want to be and that i would like to know her answer so that icould cope with it if she was gonna leave me she said she would tell me tomarrow? Why is she doing this???