My mom is suffering from dementia.  Though frail, she has the ability to dance very well in an improvised way. Because her memory is virtually gone, and her cognitive skills are impaired, she could not do any sequence-type dancing.

I look for experiences that are within her capabilities, with the full expectation that she will remember none of it the next day.  "Enjoyment of the moment" activities such as museums, zoos, concerts, etc. are good.  Movies are likely not good.

In this dancing couple, the woman likely does not realize the amount of accommodations that others are making for her.  She has a disease, and is not at fault.   In fact, I find it touching that the couple wants to continue the activity.

But they really can't.

It is time to talk with the husband, to let him know that participation by his wife is causing the other dancers to have to support her. Also, his wife seems more frustrated and confused by the dances. You can say that while you treasure their participation in your dance over the years, but it may be time to stop coming to the regular dances.  Do your research, and see if there are any activities in the area for her offered by "memory cafes" or senior centers.

Good luck.

Dan Pearl