He does

Isaac slowly pushes forward. You can feel his dick push apart your pussy. As your best friend’s dick enters your body you think “please, no.” but say, “Ah, yes.”
“Oooah,” Isaac moans. “You have no idea how long I’ve wanted to do this.”
“Mmmh, Isey.” Your feminine side says as she feels Isaac’s dick slide in and out of her. “I should have let you do this long ago.”
Isaac leans forward and puts his hands firmly on your breasts.
“I still remember the first time I saw you transform.” He says. “It was like you turned into the hottest babe in the world.”
Your female side replies with, “Fuck me faster.”
Jesus, why in the hell did your female side have to be a super horny nympho.
Isaac fulfilled your bad side’s request and said, “I had a hard-on for the rest of that day and only got rid of it after I masturbated to you in my room.”
“I didn’t know.” Your male side thought.
“I didn’t know.” Your female side said. “If I had I’d have sucked you off then and there.”
“And that was not the only time.” Isaac continued, thrusting into you harder now. “Remember that time you got horny at the beach and transformed, showing your female side topless?”
“Ugh, you put your shirt over me and got me out of there.” Your female side groaned. “Away from all the fun.”
“Well that night I masturbated to you again. Until it became a nightly ritual.” Isaac confesses. “Fantasizing about you on my dick every which way.”
God damn, you never knew Isaac had these kinds of feelings.
“Oh Isey,” Your female side says. “You finally made your dream come true. Your dick is sooo yummy. My kitten totally loves to suck on your meat.”

As you are being fucked, you see the television show a sex scene exactly like the position you were being fucked in right now. A redhaired girl was sitting on her hands and knees, looking into the camera while being fucked from behind. You looked into her eyes and imagined it must be what you looked like right now.

“Well, I hope your kitten is also thirsty.” Isaac says. “Cause I am about to give it some milk.”
“Isaac, no!” Your male voice says in your head.
“Yes Isey. My kitten needs to drink. Give it to her.” Your female voice says.
Isaac puts both his hands on your butt and starts fucking you harder. Your body starts moaning loudly now, louder than the girl on TV.
“John.” Isaac says. “I don’t know if you can hear me but …”
“He can.” Your female side says interrupting him. “He’s been trying to tell you to stop but I don’t let him.” She continues.
“Awsome.” Isaac says. “I like this version of you far better. I’m going to knock you up, keep you like this for the rest of your life and then use you as a fuckbuddy. You don’t mind, do you, Doe?”
“Just fuck me enough times per day and I’ll happily be your sex ****.” Your feminine side says.
“All right, then.” Isaac says. “Get ready, pussy. Here comes the milk.”
“NO DON’T!!!” You try to yell, but your voice did nothing.
You did however feel Isaac embed his dick all the way inside your pussy, it started throbbing and then … you felt his sperm flow inside your pussy.
“Chug! Chug! Chug!” Your female side said, relishing the sensation of getting spermed.

Your greatest fear has come true. Sperm has finally found its way inside your pussy. That of your best friend no less. However there is still one big question that remained.