Maurice,

The terms of the marriage contract would have to be changed. The phrases of "till death do us part" and "in sickness and health" would need to be removed out of the contract. Almost dead is different than being dead. What about if your partner has sustained a severe brain injury such as a stroke or is in the last stage of terminal cancer?

I see a potential conflict of interest. Can the spouse with Alzheimer's disease contest the divorce?
Has the spouse with Alzheimer's disease given permission to the partner to the contract to have sex outside of that contractual marriage, before-hand?.

Why did the partner wait so long into the progression of the disease to file for a divorce?

Who is going to be the legal guardian of the spouse with Alzheimer's disease to represent his/her interest in any settlement/court case? The same partner who is having extra-marital sex or is seeking a divorce?

In my humble opinion, If it is end stage, just wait; and provide the emotional support to your spouse, by your mere presence.

Is having sex with the wife for the greater good; providing emotional support for the spouses and keeping their marriage together? I would have to agree with Eric's answer:

http://www.medpedia.com/questions/1313-a-husband-having-sex-with-his-now-mentally-and-physically-incapacitated-wife-is-it-ethical-and-is-it-even-legal

I do not see it as unethical, once it is for the greater good. Legally, I would give the spouse the benefit of the doubt, seeing that the spouse would know his/her spouse much better emotionally, and would know what his/her spouse would agree to. As Eric had said, paraphrasing, you have to prove the case beyond the reasonable doubt.

Can the spouse comfort his/her incapacitated partner, by singing to them, kissing,caressing, massaging, petting, holding hands, etc? How do you know that the incapacitated spouse is not able to 'feel" this care and is not emotionally benefitting by this closeness?

"When there is reasonable doubt, do not convict."

The other issue that comes up in the context of my Questions is how should physicians and the nursing staff in an institution housing the demented spouse respond when the patient, perhaps no longer remembering he or she had a marital partner, engages in sexual activity with others in the institution? There is much to learn about intimacy and sexuality of the Alzheimer's disease patient and a brief discussion of the topic can be found at the Alzheimer Society's website:
http://www.alzheimer.ca/english/care/ethics-intimacy.htm
With regard to my question just posed, the site says "As the disease progresses, people may no longer recognize or remember their partners, and may seek companionship and physical intimacy with a new partner in a long-term care facility. Due to the sensitivity of this issue, family members and staff may try to prevent people from fulfilling their needs outside of previously existing relationships." There is no advice on this matter other than "If the person with Alzheimer's disease chooses a new partner, it is important to ensure that those involved agree to the relationship, whatever form it takes." and "drawing attention away from a new relationship that might upset a partner". Any suggestions from a Medpedia reader if you were the physician or nurse in such a prolonged care institution and it was discovered that the Alzheimer patient was having sex with another patient? Would you keep the two separated? Would you inform the spouse? Or would you do nothing and consider the activity as "therapeutic" to both institutionalized parties? ..Maurice.