Kono Natsu, Shoujo Wa Bitch Ni Naru [English], by Hal

Wait, what ?!? At first, I thought the story was a bit sad, but no more. And then it turned fucking dumb -_-
Here’s the gist: a naive woman shily seeking a boyfriend finds a naive young man, apparently making a good first boyfriend material. She doesn’t realize but the boy is only pretending, and things end up with sex. The day after, she realizes she’s been had and dumped shortly later… and then, saddened, she becomes a cump dump gyaru. FOR FUCK’S SAKE THAT DOESN’T MAKE SENSE

–EDIT: good news, this post is now obsolete.
Please follow that link, for a new version, with 12 more pages, a better scanlation, and absolutely better scans!