My girlfriend is a fraternal twin. I had only met Rosemary's sister once before she moved away to Europe over a year ago, and I did not remember her all that well. I knew she was hot, but I had been drinking a bit the night we met, so my memory was unreliable. At first, my twin, threesome fantasies involved my girlfriend being duplicated in an identical twin situation, but that changed once her sister Lily came back home....

Rosemary got home late after her shift at work. Lily and I went about the rest of our day as if nothing had happened. Despite the guilt and sexual tension hanging in the air we got along well, we chatted easily but there was no extended conversation. I felt bad for cheating, and she gave me time for contemplation. I wondered if things would be so easygoing if the sister's roles were reversed. Would Rosemary give me space...

The next few days were uneventful. Rosemary rotated to the afternoon shift at work, and as a result, I would see her very little for the next two weeks since she got home after I was asleep. I would usually wake up so we had a few minutes to chat when she would come to bed, but my evenings would be spent entirely with Lily. At first, we kept our hands off each other as there was a lot on our minds. It was now clear to me...