"Babe!" You reached out, just in time to grab one of her tails, causing both of you to yelp like a fox.
Wait...both?
You found yourself falling to the floor, as you realized you were going through the same type of change as your girlfriend! 9 tails burst out from your rear, as your body became covered in a darker brown shade of fur, as your penis grew a knot and turned red. As your muzzle pushed out, you felt another muzzle on yours. You looked up to see your girlfriend pushing her muzzle against yours, with a sad loving look in her eyes. "I didn't know this would happen, but I'm kind of happy it did." She said in a melancholy manner.
Your transformation finished, and you both jumped out the window to run out into the woods, sad to leave your old lives behind, but looking forward to becoming mates in due time.