Observe and document.

You jerk off at a medium speed as you attempt to finagle your phone's camera. You need to get some shots of this. Never know when it might be useful.
Jenna's moaning now, as Jack's fingers find her snatch.
"You're a dirty girl, huh? When did...mmm....when did that happen, Jen?" Jack sounds out of breath.
"If you want me to continue...shut the fuck up, Jack." Jenna's gripping his cock, staring at his face.
"Got it."
She continues without interruption, and Jack continues to finger her wet pussy. Jenna's a master oral performer.
"Oh Jenna....I'm...." Jenna bobs furiously, determined to get him there quickly, now.
"Ahhhhhh......" Jack cums, and Jenna's cheeks fill with his cum. She strokes out the last of it, swallows, and wipes her mouth as she pulls away from his fingers.
"That was yummy, Jack. Thanks."
"Wha..." Jack is rolling in afterglow, that strange and often loathsome period. "Is that...we're not going to..." he reaches for her, but she dances back, pulling up her bikini.
"Don't get greedy, Jack. I'm going down to the pool, now. You should wait a while, then join us. Dinner's at 4:00." As businesslike and matter-of-fact as you please. Her sudden, almost cruel demeanor is so hot to you for some reason.
".....ok..." Jack doesn't really know what to think, but he lays back, staring at the ceiling.
You pull back from the door. You can't wait to reclaim her. In fact...
When Jenna steps out of the guest room, she sways a little, looks around, then proceeds down the hall. You wait in the doorway to your room, out of sight. As she turns to head down the stairs, you strike.
Your hand closes over her mouth as you grab her around her arms with the other.
"Don't scream, you dirty slut..." you whisper in her ear. She squeals in surprise for a moment, and again as you pick her up and carry her into the master bedroom. You toss her onto the bed on her stomach.
"You've been bad again, Jenna..."
She looks over her shoulder at you. "I was hoping you were watching, baby." A wicked smile crosses her lips. You cruelly strip off her bikini bottoms, but leave her top and coverup.
"Why didn't you fuck him?" You lube up your dick with spit as she presents to you, ass in the air.
"His dick wasn't as nice as I expected..." she shrugs. "Besides...it was fun to tease him..."

You slide into her pussy, and find it quite moist.
"Mmm.... yeah baby." She starts moaning unabashedly. "That's the dick I need..."
You pound her slowly as you squeeze and smack her ass. "Then why do you keep looking for other ones?" She turns to look at you.
"Because I'm a bad, greedy little piggy..." You grip her hips and start slapping faster and faster against her naughty cunt.
"Yeah you are...insatiable...."
"I don't know...awwww awwww awww......." She squeezes a nipple through her top, eyes rolling back a little. "I don't know when to quit...."
"Are you going to keep looking for strange cocks to suck and fuck, you little slut?" You grip her hair, pulling her up onto her hands and knees as you pound harder and deeper.
"Y..y....yes....I.... can't....help....OOOO...." her sentence is interrupted by a spasmodic contraction of her pussy... "I'm going to cum, baby...fuck me harder..."
"I don't know..." you slacken off... "...you've been a bad girl...maybe you don't deserve to cum..."
Jenna whines pathetically... "Nooooooo......" she tries to stimulate herself, but you catch her arms and pin them back.
"Answer my fucking question and then maybe you can cum..."
"YES! I'm a greedy whore. I'll keep looking for strange cocks!! Please!! Make me cum...."
"And after you've had a strange cock?"
"I'll come tell you what a bad girl I've been! PLEASE!!!"
You pound furiously, angling for her spot and releasing her hands. They fly to her clit, and in seconds, she's belting out an orgasm that there's no way Jack can't hear in the guest room. That'll give him something to think about.
She lays in a puddle on the bed, twitching and shivering. But you aren't finished. You crawl over to her, and jerk your load onto her cheating face.
"Mmmm..." she gathers the cum with her fingers, and licks them clean. "So much nicer than his was. I thought I was going to yack...."
"I...love you Jenna." You stroke her face.
"I love you too, baby. More than anything. Thanks for taking this journey with me. We're going to have so much fun..."