Going back to what jane said, that's exactly my point, the story is getting more depressing, because when Sal is not with a woman, he feels bad. This is why he is the opposite of Dean. Dean is a just a perv, I mean, who asks their bro to watch him and his girlfriend "copulate." That's generally rude, if i were Sal, I would break his nose. But it just comes to show how much Sal respects and needs a woman in his life, while for Dean its just another object, just another thing he has.