Inspired by u/beautifullybrkn here is my take on secret sin.
The only light in the bedroom was from the vintage 1990s digital alarm clock on his nightstand.
He glanced over at it. 3:24, exactly two minutes later than the last time he looked. He had been awake since 3:00 and was staring blankly at the ceiling, thoughts racing through his head,
wishing he could go back to sleep. He turned the other way and could make out her profile in the dark, laying on her side next to him. He knew what he needed, as it had been several days since his last release. But she couldn’t know. She couldn’t know how much or how often he needed the release.
Instinctively, he reached between his legs, feeling his soft cock twinge a bit under his palm. He could do this, and it would be just what he needed to relax his mind so he could sleep. Just the thought of having a release caused his cock to stiffen a bit as he pushed the covers to the side and wrapped his hand around the shaft. Slow strokes, that is what it would take.
He ran his hand from the base of his cock to the head, firmly gripping the head and squeezing, feeling it get just a bit harder. As he gently rubbed the soft skin immediately behind the head, his whole cock tingled and it quickly reached full erection, the proud head swollen and sensitive. He could just see it in the soft light from the alarm clock, sticking up high as he stroked the shaft.
He put his head back and let his mind drift to thoughts of imaging her pleasuring him with her lips instead of his hand. Cupping the head he imagined her taking it into her mouth and sucking on it like a lollipop. This made him arch is back and inhale sharply, and at that moment she shifted in the bed. He stopped. Did she wake up? No, she is still asleep, but perhaps he should be more careful.
Switching to his left hand might make this go smoother with less of a chance of disturbing her. To his surprise, switching hands made it even more erotic. Perhaps it was the different sensation, but he could feel the tension building in his balls with each stroke. Slowly and deliberately he continued, while he bit his lip. Tiny tingling waves began to work up from the base of his cock to the tip, and they continued to grow as he continued to stroke. As the sensations grew, and built up to a crescendo, the room appeared to go white for a moment as he felt a pulse leaving his balls, traveling up the shaft, and shooting out the tip. Stroking up towards his chest, he watched as the second, third and fourth spurt of warm cum left his cock and landed with a warm, satisfying plop on his belly. Still grasping his cock, he let his body relax, feeling the endorphins flooding his brain. This was just what he needed. It was temping to just drift off to sleep, but some cleanup was necessary.
It’s best she never know. To her, what he did was sin, so he would keep his secret sin to himself, for to him it was more than just the release.
It was what he needed.
Source: reddit.com/r/eroticliterature/comments/ci102n/his_secret_sin