An interesting point. When Sandra Day O'Connor retired from the Supreme Court, the primary reason was that her husband was suffering from mental decline and was in a care facility - where he had struck up a sexual relationship with another resident who was also suffering from senility, for lack of a better word. An article I read around that time, in Slate I believe, said that such a thing was not all that uncommon among institutionalized old people. The article went through all the moral, legal, and ethical issues of such people who do not recognize their decades-long spouses, but are having a torrid affair with new acquaintance. Some try to stop it, some say let them live their last years having this fun. Overall, though it was sad; and reinforced how strong our sexual needs are.