I couldn't explain why it was always this way, but my sister and I have always been very close (and we are almost the same age, she's barely a year older than me). When we entered puberty and hormones were out of control, we kind of naturally developed a sexual relationship. I lost my virginity to her at 15 (she had a wild sex drive and lost hers to an older guy even earlier than that).
It was kind of a casual thing at first but, at least for me, it turned into a very deep desire later on. She was kind of my perfect woman: long, dark, curly hair, full breasts not too big, wide hips and a slight belly. I was very attracted to her even before we had sex for the first time, but became even more hooked after. She was quite easygoing and open minded, so when we started to fuck more often and realized we couldn't keep buying condoms all the time, we turned to anal. For three years I didn't have eyes for any other girl.
Then we decided to give up on this when we went our separate ways for college. We thought we'd move on easily, and apparently she did. We kept in touch, but she found herself a revolving door of boyfriends. For my part I didn't do too bad, but sexually, I always felt something was missing. Not very long after graduating from college she met an older guy and got married, while I kept moving from one relationship to the next. I didn't realize it then, but what I really craved was to fuck her again.
It took more than a decade, but I got my chance. We are nearing our 40s now, and she got separated from her husband. At first I supported where selflessly and offered her my place to stay when the son of a bitch shut her out of their house. Old feelings started to resurface and, well, let's just say we didn't leave my appartment at all last weekend. We fucked every possible way we knew and I came inside of her until I was dry. It was a VERY HOT weekend, but after the dust had settled she started having her doubts. She moved out to a motel for a few days, she's keeping in touch but she says she wants to think if this is right. I just know right away that this is what I want, no matter what.