As you play with yourself wondering about what to do, you feel something on your shoulders. You investigate and find your hair has grown longer and now falls over your shoulders. Looking over your body you see less hair that you used to have and your body seems to have developed more feminine curves. The only thing really missing now is your rather modest chest.
That's when you hear a key in the front door. A wave of panic sweeps over you. It has to be your girlfriend! What will she say when she finds you like this? You hear the door open and close. Noises in the living room. Then light footsteps as she walks toward the bedroom. You look nervously toward the doorway.
She stops suddenly and her jaw drops.
"Honey, is that you?" she asks, unwilling to believe her eyes (and not entirely sure because of your changes).
"Yes" You're shocked by the change in your voice.
"Why are you a mermaid?"
"I was putting some laundry away and found a tail in your closet. I was too curious for my own good. I'm sorry."
"It was supposed to be a surprise for you."
"It worked - I'm certainly surprised!"
She slowly walks over to the bed. "Do you like it?"
"It has certain...advantages..." you admit.
She runs her hand along your tail and you love the feeling. Especially when she gets to your visibly wet crotch. You squirm with pleasure and she smiles at your reaction.
"So I see."
She probes your womanhood with her finger and you moan. Satisfied at your reaction, she takes her hands off you and begins to unbutton her blouse.
"You're not mad at me?"
She shakes her head. "I was going to wear that tail for you. But since you decided to wear it..." she licks her lips. "Lets just say I have certain fantasies of my own."
Your girlfriend strips off her blouse, skirt, bra, and underwear then climbs onto the bed, straddling your tail between her legs and grinding her crotch against yours. "Pity, I would have preferred a mermaid with a better chest" she says as she leans down to kiss you.