She didn't want him to stop and he sure as hell didn't want to stop, so what was the problem here? Maybe everyone was right; maybe he was being stupid about this entire thing. Maybe. But was that enough of a chance for him to risk something that he really cared about? Someone that he really cared about? Sam knew that it was selfish of him to deprive them both of what they wanted, but people didn't seem to understand how bad things were capable of getting. Would Heather be like Jessica, the woman that he planned on marrying? Stomach carved into while she burned on the ceiling? What about Madison? Would something happen to her, thus resulting in him having to go back and kill her off because there was a chance that she'd hurt someone? Dean had said that Sam just had a bad run of luck in the past with women. Who was to say that he wouldn't in the future? Especially with his future?
He wished that he could somehow make her understand. If there was a way to just make her forget everything up to the point where they'd started liking each other, he'd do it without hesitation. If that meant that he could keep her from crossing that line, the one that separated the people he loved from the one's that he didn't, he would have. But it was too late now. There was no going back.
God, he wanted this. He wanted her, but it just wasn't going to happen. He needed for her to accept that rather than give her every reason to get more and more involved. Sam suddenly pulled away from her again, this time entirely, and took a big step backward.
"I can't do this, Heather," he said, putting his hands out in front of him. "I'm sorry. I have to go." He didn't want to give her a chance to argue or make another move. So he turned around and started walking toward the staircase. Waiting for the elevator would just take too long. He didn't have the heart to turn back around. Sam didn't want to see her reaction.