Here are my thoughts. Please bear in mind that I'm caring for my 79-yr-old husband with moderate vascular dementia on top of a 20-yr-old non-traumatic spinal cord injury. I also have a 24-hour caregiver--two men from an agency who alternate, each a few days at a time, so I do sleep at night, my husband does know me, although he is intellectually impaired, disabled, and angry and frightened and very demanding. Some of the questions posed don't fit me so well, but I still have strong feelings about this. Also I don't care about what religion anybody's trying to use to beat other people over the head or to hide behind. This doesn't seem like a religious question to me. So here goes:
Q:If you're married to someone who doesn't recognize you as a mate, or can no longer comprehend what marriage is, is that a marriage?
A:Well, marriage is a legal contract, so that's a moot point. To get out of it, you have to do it legally. But ethically, if you'd agreed on this ahead of time & amended your vows (assuming you made vows) to read "in sickness and in health, with the exception of dementia", you could say that it isn't a marriage and you had grounds for divorce. Otherwise, it seems to me a promise is a promise, and this is an ethical question about your definition of a promise and what grounds you are contemplating using to justify breaking a promise.
Q: If your relationship can't possibly be equal, is that still a marriage?
A: I'm uncertain of the meaning of this. Does it mean that you were equal to begin with, say, in strength? or intellect? or intuition? or height? or weight? or testosterone levels? or beauty? or...? Inequality doesn't seem to prevent marriage for most of us.
Q: If your loved one can't have sex, is that a marriage?
A: Depends on definition of marriage. In my state it's a legal contract. But yeah, I know, that's not what we're talking about.
Q: If you don't want to divorce a spouse with Alzheimer's, is an affair ever viable? Or does "in sickness and in health" apply no matter what, and even if your loved one has Alzheimer's for 5, 10, or 15 years?
A: Again, ethics. Did you mean it or not when you said (if you said) "in sickness and in health", etc., and did you mean it in the traditional sense, i.e. exclusivity? If you meant it when you said it, then again it's the question of whether you can live with yourself if you break your promise.
Q: Should more of us be discussing this with our partners before the first hints of mild cognitive impairment appear?
A: Certainly, if you intend to have conditions on your promise, they should be stated from the beginning. This gives the partners the chance to bow out before the promises are made if they don't like them.
Obviously I'm concerned about the individual trying to justify breaking a promise based on the fact that they are horny. In my experience, one usually regrets this.
Of course, all the other ideas about getting out there and continuing to live and grow as a human being are terribly important! But not easy to implement. I just think wanting to have sex is a pretty flimsy justification for having an affair under the circumstances. I wouldn't do it because I'm virtually certain it would make me think less of myself. And I don't need that right now!