Ashleigh was noticing this mission and, honestly, her head was spinning at how quickly he was plowing through everything.
For the very first time since they'd started dating, she felt very rushed and, well, slightly stressed. Which was probably what caused her to blurt, very unromantically, "I'm not going to have sex with you tonight."
There was no doubt about it, he was definitely making her feel good but she simply couldn't... it was too much. As much as she wanted to make out with him, the rush, the lack of studying... she couldn't stay focused.