Today, my girlfriend's parents were out, so she invited me to stay overnight at her house. The thought of sleeping together with my girlfriend made me excited, and that night we both enjoyed having sex, making me feel thrilled. Unable to resist any longer, we engaged in a "round" together. I wanted to have unprotected sex and ejaculate inside my girlfriend, but she insisted on using a condom. With no other choice, I put on a condom and had sex with her. While we were passionately engaged, my girlfriend's sister suddenly walked in, saw us having sex, quickly apologized, and left. It turned out that her sudden cancellation of plans brought her back home. Her sister Non is a very beautiful girl, especially her large breasts that captivate any man's gaze. After chatting for a while, my girlfriend went to shower, and Non approached me, pressing her breasts against me. "You can ejaculate inside my uterus if you want." I couldn't resist her invitation, and whenever my girlfriend was away, Non and I would get intimate, continuously ejaculating inside her uterus until... my girlfriend suddenly came back early and discovered everything...