You grunt as your body's size grew up and outwards as you gained muscles you haven't had before as your cock grew feline-like and became 16 inches long and 3 thick with a knot that's another inch wide. You turned to see your girlfriend as she slowly tried to get away from the fucking before a tentacle vine entered her ass through her clothes as others went in them and ripped them apart as she gasped in surprise before you leaped on her and pulled the one in her ass out of her. You still had some of your mind and unlike the rest of your group pulled her away from the vines into a nearby clearing that is fairly large for one in a jungle without the fuck vines hanging down from the trees thought you can still smell the scent of them which was what drew your group to them before they started rapping everyone. However it was for a different reason than Jess was thinking, she belongs only to you.
Jess was about to thank you when you grabbed her by the chest and pulled her up and lined her pussy with your cock under it before letting her drop on to it. She gasps in pleasure and pain from it before you grab her legs and use them to push her up before pulling her back down as you thrust up into her pushing more of your cock into her as you moved to a tree and leaned back on it to focus more on turning her into your slut. "Or-Orion stop pl-please!" Jess begged you to stop raping her as she moans as you nipped on her neck, but you paid her no mind for she will give in soon.
Jess's body soon starts to grow fur starting from her cunt and slowly spreading out from it as two pairs of teats appear below her breasts. You feel your cock hitting something making Jess moan louder as she had stopped begging you to stop, with five inches still outside of her pussy and conclude you are hitting her cervix and thrusted harder into her wanting to cum into her womb.
"A-ah, yes more! fuck em more, breed me!" Jess moans as she gives into the pleasure as her body is now half way covered in fur which is golden brown with spots meaning she becoming a cheetah as the teats grew into two more pairs of breasts growing to dd-cup along with the first pair of them which was a c-cup at first as the fur spread faster as fangs grew in replacing some of her old teeth.
You thrust into your soon to be first mate as you feel her cervix giving in to your thrusts and soon enter Jess's womb hitting the back of it making her yep in pleasure as her eyes rolled back as it bulge out from her belly with each thrust before she started climaxing. You thrust into her a few more times before stopping as your knot grew and harden locking the two of you in place as you cummed into her womb making it bloat outwards due to the knot keeping it trapped in her. When you finished she looked eight months pregnant with twins, at least likely more for cat birth to litters of kittens/cubs.
You pulled out of Jess a few minutes later before the two of you lay on the ground with you leaning on the tree. Jess has just finished transforming when she climaxed and she looks up at you as she rubbed her head on your neck as she held her belly as it slowly shrinks from your cum pouring out of her cunt. You soon got up as you looked for resources to build a new home in the clearing which is near a cliff you hadn't seen for the two of you can't leave without people asking what happened you the two of you and your group at the least, if not the government dropping you two into a lab. Beside you wouldn't mind turning and fucking more humans into anthro feline females to breed with your kittens.