You push your cock into her cunt as she screamed in pain and pleasure. You fucked her hard as your pre-cum begin to enter her body. She managed to get out from under you but you pulled her back with your magic but she got away again a minute later. You decided to wait as she has some of your pre-cum in her ans is showing signs of starting to transform.
Several minutes later she was now in mid-transformation. Fur was coating her body with a stubby horn that's growing and a tail had already formed that was to the side to reveal her transformed vagina as it winked at you. She looked back at you and nodded and let out a sound that sounded halfway between go ahead and a whinny with her mind being shifted towards a willing broodmare. You didn't need any further motivation, you were already horny from the sex being cut short twice. You mounted her and pressed your cock against her vagina for a moment before you thrust deep into her as she neighed loudly and you thrust into her faster and deeper as she started to move with your thrusts, her flanks rubbing against you.
The feeling of animal mating was strangely exhilarating even more the second time. You had a lot more control over your thrusts and instincts this time and you were loving it as you thrust faster and deeper into her. You could actually feel her vagina growing larger as you thrusted faster and deeper and she let out more whinnies and neighs as she enjoyed the feeling. You were already aroused and after one more thrust your cock stiffened as you blew your load into your girlfriend. Her vaginal muscles clamped down on you and squeezed your cock as more semen was drawn out of it and impregnated her.
You neighed and dismounted your girlfriend, she had been turned into a beautiful sliver furred Unicorn mare that shook her head and nuzzled you gently. You looked into her eyes and saw no trace of your former girlfriend.
"Very good, now we just need a Pegasus stallion and a mare and we're all set," The attendant's voice said as she entered the stall. As she moved to your mate, You decided to...