I first heard about this film through its music. The late Piero Piccioni was one of Italy's finest composers from the hey day of Italian cinema in the 60's and 70's.
The write up for this movie descibes it solely in terms of sex and eroticism...
性爱学分 SCORE (1974)
Also known as: The Score
Description: Liberated ’70s couple seduce another couple into experimentation with bisexuality and group-sex.