“I know you're my husband, but you're pathetic when it comes to sex. That's why I fuck our son now. His cock is twice the size of yours, and he makes me come so fucking hard,” Cindy told her husband, followed by a cruel giggle.
Greg's voice cracked as he dropped to his knees in the living room, hands clasped together like he was praying. "Please, Cindy, don't keep doing this. Don't keep having sex with our son. I'm begging you—I'm on my knees here." 
Tears streaked his face while he looked up at his wife, who stood calmly by the couch in nothing but a bra and panties covering her giant tits and throbbing snatch.
Cindy sighed softly, almost sympathetically, and stepped closer so her bare feet were inches from his face. "Greg, sweetheart, I love you. But you know I can't keep pretending. My body needs more than what you can give me."
"I can try harder," Greg pleaded, voice trembling. "I'll do anything—pills, therapy, whatever you want. Just don't keep spreading your legs for him."
She reached down and gently stroked his hair, her tone patient and almost maternal. "It's not about trying. It's biology. Your cock is small, and your drive has been fading for years. I need a long, thick dick that can stretch me open and pound me until I'm shaking. I need someone who can fuck me like an animal, make me cum again and again without stopping. Our son has that. He's young, hung, and his balls are always full."
Greg's shoulders shook. "Cindy, he's our son—"
"And he's exactly what my pussy craves," she cut in, voice still soft. "Every night I lie there aching, wet, desperate for a real cock to wreck me. Yours just doesn't reach the places I need. It was never your fault, baby. You were born with what you have. But I was born with this hunger, and I can't starve anymore."
“It's not fair,” Greg uttered in a defeated tone.
“You're right, it's not fair… it's never been fair… TO ME,” Cindy stated. "When he pushes that fat dick inside me, I finally feel full. He'll hammer my cunt until I'm squirting down his shaft, then flip me over and do it again. I need that. I need it so badly I can't think straight."
Greg's forehead pressed to the floor. "Please... please don't let him breed you."
Cindy crouched, lifted his chin with two fingers, and kissed his forehead. "I'm not choosing against you, Greg. I'm choosing what my body demands. Your little cock and tired libido just can't keep up. It's about science, not love. And if you could see him buried balls-deep in me, pumping load after load into my womb, you'd understand why I had to have him.”