I went over to my girlfriend's house and was having sex with her when a beautiful woman suddenly appeared, staring at us! Shit, her older sister caught us! I panicked, thinking she'd be furious—but instead, she started secretly seducing me. I love my girlfriend, but I couldn't resist the forbidden thrill of my sister-in-law's advances. Her techniques were far better than my girlfriend's, and the pleasure was so intense I ended up passionately fucking her repeatedly. I knew I shouldn't get caught, but the excitement was addictive—I just couldn't stop this illicit affair!