As the afterglow of your orgasm fades your body starts to return to its previous form. Your hooves become feet again, your tail pulls in, your face becomes human once more and the fur recedes. You're hairyer then before, more muscled too, but definitely human again. All except your cock. Your magnificent donkey dick is safely back in its sheath and you're glad that that part of you has remained bestial.
Your girlfriend has returned somewhat to normal too. She is slightly bustier then before, her nipples still a striking black against her creamy skin, but they wouldn't poke through a bra now. You suspect that she still has a mare cunt and the air is still pleasantly laced with its pungent scent. She stands and gives you a kiss.
"A pity," she says. "I was just starting to like the idea of being half donkey."
"Don't worry," you say. "I feel like we'll turn back when we are aroused again. And then I'll ride you like an animal again!"
"Is that so, stud? We might have to get a real donkey to ride me so we can compare."
You look into her eyes and realise that she is serious. There is such utter depravity in her soul and you cannot contain the lustful delight it gives you. You lift her sharply into the air and she splits her legs wide open, ready to be pierced by your donkey dick as it springs from its sheath. You bring her down just as sharply, your beastly dong burying itself to the hilt inside her steaming snatch, and then you slam her bodily against the wall.
Your feet crack into hooves and your digigrade legs add extra power to your hefty thrusts. You nip at her neck with your buck teeth and she does the same to you, and her ballooning tits pillows out to the side as your weight crushes against her.
"Yes, yes, EEEAW," she brays. "Find me a donkey! Make me fuck it! I have to know! EEEAW!"