Personally I believe Marriages survive on intimacy and sex. Once the intimacy is gone from a marriage, the marriage starts to suffer, especially if it has been months since the couple has been intimate. The spouses start to act like roommates. One spouse is not getting their sexual needs met, so they look for sex elsewhere. This leads to infidelity and divorce. In short, a lack of sex can lead to dissatisfaction, which will ultimately kill a marriage.