Molly's transforming body pumped you in a way a human body couldn't. Even as you were feeling immense pleasure you were feeling a strange sensation in your groin area. You looked down between your bodies to see scales starting to radiate outwards from the base of your penis while the shaft remained inside Molly. You tried to pull out, but to no avail.
"Molly..." you managed to say, but she was lost in the throws of orgasm and transformation.
Finally you felt Molly's muscles slacken and you pulled out, falling backwards into the tub. It was clearly too late with scales working their way up your abdomen and down your thighs. Molly remained standing, leaning against the wall and breathing heavily.
"Molly...I'm transforming too. Turn off the shower."
She opened her big fish eyes and looked at you. "You are! Yay!"
"Yay?"
"I don't want to be the only fish person" she said. "I'm so happy you'll be my mate!"
Instead of turning off the shower, she adjusted the showerhead to spray you down even more as the scales continued to spread across your body.