Describe what's going on, beyond "they had hot sweaty sex and collapsed in exhaustion afterwards". If he touches her, are his hands smooth, rough, calloused? How does she feel to him? Where does he touch her? What does he smell like? How about her? What does it taste like when they kiss? What sounds are they making? Sighs, moans, grunts? Describe the foreplay, if there is any - done right, it get's the reader turned on too.