I think the movie just proves its point
First of all, I think it's great movie and I liked it.
At the beginning we say Caleb stating that all women are whores and they will *beep* you over everytime. At the end we learn, that it is in fact true (from the movie's perspective).
So it proves the point and there is no deeper meaning in it, still, I enjoyed it evry much, great perfomances. Only thing that hated was Emma's looks. She looked really like a little slut all the time (and I believe that was intentional) and I couldn't feel any connection with her character.
And I am not saying that all women are whores or anything. What I would assert is that we all (men and women) are selfish in true meaning of the word and we all act to fulfil our best interest. That's how we evolved and there is nothing immoral or unjust about it. People just need to accept this basic fact and start enjoying life.
And when I hear complains about "you're selfish" what they are really saying is that "you do not do what I want you to do to meet my own selfish needs so I better would try to shame you and pretend I am on a moral highground" when in fact, we are all pretty much the same (in this regard).
So again, great film, great acting and great time spent.