How to prepare a family and their loved one about moving to assisted living?

Here's an article with 50 Tips on Transitioning an Elder Into Memory Care AL:

https://www.seniorlink.com/blog/50-tips-on-transitioning-a-loved-one-to-memory-dementia-or-alzheimers-careyour-blog-post-title-here

Question..
Is the husband moving in to AL with the wife? Or is he moving her in?
You mention cognitive issues..if she has dementia of any type I think he should be looking at Memory Care NOT Assisted Living.
The vast majority of AL allow residents to freely come and go. They must sign in and out simply so the staff knows if they are in or out of the building in an emergency. Because of this she could wander out on her own.
Memory Care the units are key coded so it is less likely that a resident could leave without leaving with someone that has the code to get in or out of the unit.
Now that that is out of the way....
As he narrows down the selection to 1 or 2 facilities he can arrange a "Respite" stay and they can both stay there as a Vacation of sorts or he can place her for a few days while he gets a break. Most facilities will do this. It must be pre arranged as many areas have medical requirements for TB tests that can take a while. (Where I am a 2 stage test needs to be done unless a blood test is done)
She most likely will need a physical as well.
If she does have dementia a week in Respite is not going to give him a full picture as to how she will adjust though.

So many people have a bias against facilities. Yet there are many advantages that families don't know about unless they investigate. For instance, speech therapy, which my SIL gets at her memory care home. Interaction with others. A pool for swimming and exercise. At the assisted living where my mother lived for a time, there was a memory care unit. The facility had a live band a couple of times a week with male dance hosts to dance with the ladies. One of the memory care patients was fairly young, maybe about 50 or less, and she had early onset Alzheimers. The memory care staff member would bring her to the dances, where she'd get up and dance alone or with a dance host. She had a big time! We could see the joy on her face every time she danced. If she'd been at home, she wouldn't have had that.

When taking with the family, point out the benefits that they might not have thought about.

Simply ask them to let you know if they have any questions, and answer those questions to the best of your ability. Many of those questions will be answered by the facility itself, it is is important they take the questions to that source. You can help them with a list of questions. What would YOU want to know if this were you? Help them form their thoughts into questions.
What are your levels of care?
What dictates when a patient moves to a new level of care?
What are the costs of levels of care?
When do you do raises?
Do you do special diets for dietary needs?
What safeguards are in place for my loved one in terms of wandering?
Are residents checked at night?
How are you staffed?
And etc.