There's a number of things that could play into this...she could have been high from that good-good and just living in the moment, could have been starstruck or shy, or just even flat out could have been uncomfortable with the idea of this married man caressing and laying on her for a 5minute song. This isn't the 90e or early 00s. You don't have to be overly sexual anymore in order to perform a song or get a conversation going. He should have met her at her comfort level and just moved on. Usher took an L with this one and his ego ruined his fake "humble" attitude he always tries to protray.