Brother/sister marriages, especially with younger people, have a very high rate of divorce. Going through life without sex...that's an awful long time. Doesn't matter if she believes that one or not...it is a fact. Out of 10 married people I know...close friends, my sisters, semi-close workmates who are willing to talk about it, only one is a brother/sister marriage, and it is not a happy one. In fact, this woman I know is having an affair. Her and her H have not had sex in 7 years and while they used to argue about it, the subject never comes up now. She told me now, if he approached her, she has no desire for him at all and actually cringes at the thought...that too can happen in time if differences are not addressed in some way. She only stays because she is now 56 and doesn't want to suffer financially. I'm not condoning affairs, but that is what happens sometimes with a marriage like this. Younger people typically get out at some point...but I've really never known or heard of anyone being so adamant about sex as your W. Sure there are people like her...but she is not the norm. I'm not staying all of those 10 people don't have problems within their M, but they do have a sex life with their spouses...more than likely a normal sex life that they can live with.