Your girlfriend changes mentally

Both you and your girlfriend were very obviously enjoying this. You began to cum inside her, and after pulling your rock hard dick out, your cum shot all over her body as well. Not yet satisfied, your girlfriend began to make annoyed sounding noises, and you entered her once again. While both of you should've been tired and finished, it seemed that you now had more energy than before, moving back and forth even faster, more energetically. Little did both of you know, your girlfriend was experiencing some changes in her head. Her brain started to physically shrink, things that seemed normal to her before were well beyond her mental capacity now. You noticed that even though her expression was that of pleasure, the intellectual sparkle in her eyes vanished. All that was left was a glassy and stupid stare. Shaking the though out of your mind, you continued having the time of you life, but little did you know, your cock inside of her was the only thing causing your girlfriend's mental changes. Lust took over most of her thought, making it much easier for the room to melt and reshape her mind. When all was said and done, and you finally pulled yourself out of your girlfriend, she was left at...