Community of Women by Sheldon Lord

'When the last commuter train pulls out of the station, it leaves behind a... Community of Women'

Maggie, a secret lesbian married to a gay man for appearaces, who sets her seductive third sex sites of Elly Carr, a woman who sleeps with any man who comes around when her hubby is away — she has been a nympho since her days at Clifton College. But when Maggie does get Elly into bed, Maggie convinces her the nymphomania has been misdirected, that no man has ever been able to satisfy her because she needs a woman’s lusty tongue and touch.
(vintagesleazepaperbacks)