Take her.

She's so beautiful: young and so different than you thought she was. All that flirtation, the sexual acting out, all of it, was a defense mechanism. When it was stripped away, the beauty of her character shined through, making her outward beauty even more irresistible.
"So, maybe we should-" she gasps as you roll her onto her back, and kiss her deeply and passionately, sliding your body to align with hers. Your growing bulge rests against her crotch, and she moans into your mouth.
"James..." your name on her lips is like a kiss itself. "I... need you."
Before you know it, her shirt and yours are off. Her skirt is hitched up around her waist, and her legs are wrapped around your head as you explore her pussy with tongue and lips. Her thong is wrapped around her left ankle. Her pussy is neatly shaved, tight and very cute. Tasty too.
"Oh... That's so good... better than anyone ever- Mmmmm!!!" she cuts off as you attack her cute little clit with your tongue tip, flicking and swirling. You also begin probing her cunt with your thumb.
"James? Are you going.... are you going to give me your cock?"
"That depends..." your raging boner protests, but you continue..."Do you want my cock, Tara?"
"Of course..." she smiles down at you before another wave of pleasure forces her to close her eyes and moan. She sits up, unhooking her bra and freeing her sizable tits. They look even bigger than they are on her short frame.
You push her skirt further up over her hips, and free your cock from it's prison. Her pussy is nice and wet, and you use some spit to prepare the entrance.
"Give it to me, please..." you grasp her tits with a free hand. They feel as lovely as they look.

In only a few moments, you are lost in the rhythmic act of infidelty, taking your son's girlfriend on the hood of your father's car.
"Oh, fuck... I love getting cock from a real man, James." she's writhing lewdly against the windshield. You're a little concerned about sliding off, so you back down the length of the hood, bringing her with you. As you stand her up and turn her around, she sighs with lust.
"Yeah, baby. I like this..." she lays her tits flat on the hood, and you pound her from behind.
"Unf..Unf...Unf...Uh..Yeah..." she bucks against you as you pound her young pussy, really giving you a good fuck. Her upper half is probably leaving a sweaty impression on the hood.
"James...you can come in me if you want..." she looks back; her face is cute and sincere. "I don't mind."
"You're on the pill?"
"I take the shot." She rebounds harder on your pumping cock, and starts making little whimpers. "Oh fuck that's a great dick, James. It's really...hitting...eve..ry...place..." her eyes suddenly squeeze shut, and she lets her head fall onto her hands as her body quivers in orgasm.
"Nnnnnnnnnnnnnnn........" her low moan is so erotic. You can feel your own climax bubbling.
"I'm going to cum, baby." You suit your words a second later as you paint her insides white.
"Yes.....oh it's making me so full...." her words are slurred; she's cock drunk from her orgasm.
You pop your softening dick free, and cum drips out after. Tara turns around and goes to her knees, sucking on your diminishing manhood to milk the rest.
"Ah..Tara! That's...!!!" the sensation is overloading your brain. She pops free, and slurps the last bit of cum into her mouth, swallowing with ease.
"You taste nice." She stands up, but then sits back hard on the hood as her knees wobble. "Damn. You fucked me real good, James. I can't fucking walk."
"Yeah..." the reality of your actions is coming home now. "Fuck..." You put your cock away, and locate your shirt. "I fucked up real bad."
"I'm...I'm sorry. I always fucking do this." she puts her head in her hands.
"Hey, I made my own decision. It's not your fault. I'm a grown man, I'm responsible for my own dick." You take her by the hands and stand her up. You give her a kiss, and she hugs you tight as you do.
"We...we can't do this again, Tara."
I...I understand." she looks disappointed, but then accepting.
When you get back in the car, your phone is buzzing.
"Hey, Jen."
"Hey we just got back, where are you?" her voice is a little slurred. She must have had a good night.
"There was a little incident at the Off-Kilter, so I went to pick up Tara. Her car wouldn't start."
"Incident?"
Tara grabs the phone. "Hey Ms. Jenna. Sorry. Some creep at work tried to touch my... private area, and when I threw a drink on him, my boss got mad at me and sent me home. But it's okay." she switches on speakerphone. "James tore him a new one. He was bringing me back home to your house, but I asked to sit at the park for a while to calm down, and I lost track of the time."
"We'll be back in 3 minutes Jen." You start the car.
"Ok! when you get here, Tara, we can talk about what happened if you want."
"Thanks, Jenna. I'd like that..." Guilt plays on Tara's face.
Done is done. You head home, and try not to let the guilt consume you.