You do realize that sex doesn't equal love. In fact I have hated a couple people I have had sex with. Assuming jus tthe one sex scene we had was at a point where he was about to go commit suicide shows Sam wasn't in what would call any rational mind set.
But my point about Sam and demons is he hates them. ANd yes he put up with Ruby. He didn't give her free reign, he has shown disgust, distain, and hatred towards her. She had to do many things to earn trust from Sam. BUt he did build a trust for her, as long as she toed the line and helped him reach his goal. She never could push him like others such as Dean or Bobby could. And we see disgust in is eyes about her (and about himself). But as he was focused solely on his goal,and she was a means to an end, he put him with her, again only as long as she toed the line.
For example, if she would have killed Dean (like she wanted to, over any number of occasions) Sam would no longer put up with her. If she didn't help him in what he needed, he would no longer put up with her. If she started killing again, sam would have no longer put up with her.
See my point.
We see no emotional attachment to the character of Ruby from Sam. We see a dependancy on her blood, and and how she feeds his need for vengeance, but nothing else. No terms of endearment, no joking light hearted comments, no levity, nothing.
