Pretty disgusting
I don't care who wrote the story, it's preposterous and revolting. Only in the land of film does this seem plausible but if it were true it would be depraved. Two best friends who live next door to each other and are there for the birth of each other's sons and presumably the raising of them, proceed to have wild sex with them.
Insane.
I agree with the other post that said if the gender roles had been reversed this would be a banned film but it is no less ridiculous. I'm not even talking about abuse or rape - not at all. And if these two friends had never met each others sons, then I might have suspended my disbelief (revulsion). What I find most distasteful is that we are to assume its natural that you could see a child born and watch him grow, be a second mother to him, see him go through all his adolescent phases - and then start having sex with him.
No. There's something wrong with these women that a lush string soundtrack and a downbeat ending does not really cover up or make more palatable. It's all so "romantic" on the page but it feels like no one involved really gave this any long thought.