One Page of Love (1979)

Two beautiful sisters share a dark secret. Manon, disturbed and childlike, lives a reclusive life while her sister Suzanne provides for all her needs, including male companionship. This arrangement backfires when Suzanne falls in love with Rick, one of her pick-ups for Manon. This situation is further heated when Rick is attracted to childlike Manon and a conflict grows out of this complex love triangle. Rick finally breaks the cycle, takes Manon away from her sister's influence and puts her into therapy. After a time, they decide to marry and invite the estranged Suzanne to the wedding. The shadowy ghosts from the past, however, descend on the ceremony and another Page of Love is torn out.