He wants it too, you go through with it

As David you'd gotten to put your penis into Jessica's vagina only once, though you've lost count of the mutual masturbation and oral sex you and Jess have enjoyed together. The duplicate David's inexperience shows, but your combination of David's and Jessica's selves and memories helps you to guide him to something much better than that earlier screw. Sex as Jessica with a copy of your David self isn't worlds better than being Trish and having Jessica eat you out until you'd had three orgasms, but it's deliciously perverse, with a whiff of nastiness and narcissism that both you and the David clone truly relish.

"So, I make a better girlfriend than she does, don't I?" you ask him.

"Yes. I wish you'd stay Jessica," he says.

"What, leave the girl you love as a girl suit and have another you wear her and impersonate her, possibly for the rest of her life?" you ask, pretending to be horrified.

"Definitely," he says. He knows you too well. "As long as there's a Jessica, who cares who's inside her?"

"Clearly you do," you say, "'cause you want me inside her."

"It's so much more intimate," he says.

"You know, you think you're intimate with me," you say, and it's easy to sound purely like the real Jessica. "You get to fuck me, but I get to be me! Now that's as intimate as anyone can get!"

You cuddle a bit, talk a bit, and...