Ah... a classic "betrayal during consensual trashplay" story. I've read a few stories along such lines on here, though this one has quite a twist at the end compared to the others by having Alex change his mind. (which I was thinking might be the case due to the vibrator still working, but I wasn't sure until the end... great use of foreshadowing!) I'm sure after that little stunt, Kaylee will be on thin ice for a little while. I'd guess that even if she does manage to stay true to him, she'd better hope Alex doesn't suspect otherwise, or she might find herself in a similar predicament once more. Though, I suppose, such is the risk when playing with trash...
Thank you for sharing this story you two!