Husband with Alzheimer's won't let his wife out of his sight and becoming a little aggressive.

A little aggressive his way or the highway? I don’t think so.
Caregiving can only be done on caregiver’s terms, which include frequent breaks from it, i.e. respite care.
She needs to talk to few professionals.

There is help for her. She places him in LTC with Medicaid paying. She will become the Community Spouse, remain in the home, have a car and enough or all of their monthly income to live on. Have her set up an appt with a Medicaid caseworker.

Tell your friend he needs meds for anxiety, which may help with the shadowing. If he becomes either literally or verbally abusive, she needs to call 911 and tell them he is not himself and is being aggressive. She should NOT tell them he has dementia or EMTs may not come at all, since dementia is not considered a medical emergency. But if you call for police help for his aggressiveness, then it may be possible to remove himi from the home for evaluation (Baker Act). At that point she goes to wherever he is and tells them 1) she is not his caregiver and 2) he is an unsafe discharge. She should not believe anyone where he is being held that they "will help her" if she takes him back home. This is a lie they tell in order to get him discharged. The hope is that he will go into the psych unit where they will hopefully get him on meds for anxiety and aggressiveness. If he improves, she can consider taking him back home.

https://www.agingcare.com/articles/shadowing-behavior-in-dementia-470434.htm

What you describe is *shadowing* behaviour. I will look for an article.

I was informed by a pamphet in a nursing home that shadowing behaviour was #1 reason someone with dementia is admitted to a nursing home/memory care. Tops even incontinance as so stressfull on the main caregiver.