Nick is having inner conflicts here.
He is used to his Navy ways of getting what he wants. For guys like him, it is the thrill of the hunt and conquer. Sex has always been about Lust.
Here he does Lust after Jeremy, but he knows there is something more. He doesn't want to hurt him, both physically nor emotionally.
This inner voice we hear is his old ways of bedding down Tricks. His raw desire is urging him to pillage and plunder. But he is trying so hard to pace himself, even using some of his old relaxing techniques on Dupree that he used to use on virgins before.