I deeply loved my girlfriend, and we were both ordinary people. I had no deviant desires and was satisfied with normal sex. But when her older sister suddenly appeared, my sexual preferences gradually began to warp and spiral out of control. Her sister, who loved cleaning, unconsciously exposed her sheer, see-through ass and flaunted her abnormally large, voluptuous buttocks. The sight of a thong digging into that massive ass, and the excitement of having sex right beside my girlfriend while her sister was nearby—it was all so fresh, so addictive. Pressing my face against her sheer ass, feeling it crush me with overwhelming pressure, bringing me close to a euphoric death. The urge to pull aside her thong and thrust in, wanting to be flattened under her full weight. Once again today, I give in to my twisted desires and cheat on my girlfriend.