You do

"MMM...this is pretty damn hot John..." Sam whispers in your ear as you undress her and lay her on your bed as you mount her, your dick sliding between her legs and into her tight pussy again, "...knowing I'm fucking you behind his back and that you're the one that knocked me up."

"DAMN girl...I didn't take you for having such a slutty side..." you tease her as you start to thrust in and out of her, her back arching as you start to give it to her again, her hips swaying back and forth around your dick.

"UH...OHGOD...there...I...guess...you...bring...it...out...of...me..." she purrs as she throws her head back and her eyes roll into her head, her body starting to go limp as she shoots her cum all over your dick.

"I sure do love it when you cum for me Samantha," you lovingly tell her as you feel her pussy clamping down on your dick, pretty sure that you had fallen so hard for her that there was no turning back.

"OH...GOD...and...I...love...it...when...you...cum...inside...me..." she moans as you look her in the eyes, kiss her and cum deep in her tight cunt, her walls pulling on it as you empty another load into her and pull out of her.

"We're gonna do this every day we're on vacation together," she whispers as she places her head on your chest, "but right now, why don't you let me do something for you?"