I originally thought it was bad, but now I'm thinking if both people want to have sex, and they sleep together...if he loses interest and stops talking to her in a kind way, it's okay because they both are getting something out of it and are both consenting, its not like he promised anything to her, and its her choice to sleep with him...I mean its kinda mean to just have a one night stand, but maybe he did just want to sleep with her...