Lori Hollet: Lesbian? by Monica Robertson

From the back:

Lori's experience with men was negligible. But she knew all there was to know about women - all the way from the identical faces and delectable bodies of Dolores and Maria with their incomparable skills, to the oddity of Susie and her need to be strangled, smothers, hurt in any and all ways. She knew all about Ellen Martin's six-foot-plus body and her enormous, masterful strength. But her most delightful knowledge was that of Carla Kingman's insatiable hungers.

And then The Stacker came along.