You thought it must be a troll on CL that night... there's no way the ad you saw was real. A hot girl wanted to get together, and all she intended to do was ride your cock for a while until she creamed all over it. This has to be a joke.
A few hours after your conversations though, it isn't a joke and she's in your house with a glass of wine you gave her. She's confessing to you, how it's been quite the burden lately in her day to day being all horny. All she wants to do is ride your cock. So. Bad. She has a craving, and you're ready to just get comfortable and let her ride you. No strings attached. You found yourself a legitimate cock-riding slut.