Female masochism at its most overt

In Serge Gainsbourg's film Je T'aime Moi Non Plus (I Love You, I Don't), we get to witness female masochism at its most extreme and overt, where Gainsbourg's real-life wife, the provocatively stimulating Jane Birkin, plays Johnny, who falls for Joe Dallesandro's gay boy Krassky and spends the remainder of the movie trying to satisfy him sexually, although he can only get off through anal sex, which proves to be excruciatingly painful for our heroine, who doesn't care because she loves the boy, see, and she hopes that somehow he will be transformed by her love and devotion. He's not.

What does this mean? Is it a metaphor for male/female relationships, where women are, sadly, prone to being treated like garbage by the (generally unworthy) men they love? The film doesn't offer any judgment one way or another, which of course is soooooo French, and a good thing, in actuality; the actions of the characters speak volumes without any preaching being necessary.