She giggles as she starts to change. "What's so funny?" you ask.
"Oh, I just know exactly what your reaction is gonna be to this, and you're gonna be super ashamed of it," she smirks. As she undresses, you see fine, purple hairs slowly emerging all across her skin, and you realize she's growing fur. Her feet and toes start to reshape into three-toed paws, and when she looks at them curiously, you see they've got pads on the bottoms.
In your pants, you're rock hard. You aren't proud of it, but you're kind of a massive furry, and seeing your girlfriend's body adopting animal traits is amazing. She steps forward and kisses you, her lips not too furry to be weird to kiss, and you feel her nose is different against your own. When she pulls away, it looks flatter and more rounded, forming part of a subtle muzzle. You also see her cheeks twitch as whiskers emerge from them.
Up until now, you haven't really been sure exactly what kind of animal she's turning into, but then two big changes clue you in. Her ears shift to the top of her head and rapidly lengthen, and with a small pop, a round, fluffy tail emerges above her butt. As she steps toward you, you don't think you've ever wanted to fuck her so hard in your life. "Like what you see?" she asks.
"Y-yeah," you mumble.
"Good," she purrs, cupping your cheek with her soft, fluffy hand. "'Cause I'm realizing something about turning into a bunny girl. It gave me a bunny's sex drive, too." You feel like you could cum the moment your body touches her flesh.