Years back when I was just dating my 3rd wife, I also met her two sisters. Third wife to be would stop seeing me from time to time. During one of those periods, I asked out one of the sisters(single). More to she what she knew about the situation than anything else. We did have some enjoyable dates, just dinner and talk mainly. Over time we did talk about fucking but decided not going there. Little did I know that my 3rd to be was from a family where sex was a sport. Later, when my 3rd and I got back together, for good, she commented on how when she questioned the sister I dated, she and I had both said right out that we did not fuck. Of course, I would have liked it if we had, but things worked for the best. The other sister was married to a very nice guy, but I heard that he didn't feel like fucking anymore. And after a few years, my then wife, said that she was hoping that I would fuck this sister. I dream of such things, but while I liked this woman, I just couldn't get hard when I was around her. What a revolting development
I also learned that my MIL had died about a year before I came along. The reason I mention this is that she was known to fuck every son-in-law in the family. (and there had been more than a few) Interesting bunch to say the least....
What ended things was my daughter-in-law fell in love with me, and that got to be a problem. My wife said that she didn't really care what DIL and I did, as long as we didn't fuck. We didn't, but.... it was very frustrating for both of us.