FIL and MIL share a room at NH. He has a terrible temper (NH knows this very well). He and MIL fight a lot. Usually not physical. We visited for Father's Day and notice a bandage on her leg. We asked her what happened, she didn't remember (Alzheimer's) but he blurted out " I kicked her because I was frustrated. I was mad. I did it on purpose!" We know he lied to NH when it happened. My husband is calling NH social worker tomorrow when she's back from her weekend off. We will not allow him to do this, he's such a big jerk. He refuses to accept she has dementia and gets angry with her when she forgets things.
Sounds like a toxic long term relationship. Perhaps he needs to be evaluated for obvious anger issues. Even as seniors, the domestic abuse can be bad. Probably he's been abusive and she's been acquiescent for years and years.
I'd let the staff and drs at the home deal with this. Obviously, you need to keep mom safe, and maybe that will come at the expense of them being separated. I don't know.
I once had clients who had been living in a one bedroom ALF. When the wife required much more care, the family (stupidly!!) just moved them BOTH back to their condo, and tried to facilitate 3-8 hr shifts of care, to save money. I went in for the initial meet and greet and the woman is on the floor, screaming, the other aide and I attempted to get her up and she was swinging wildly and hit me in the eye. 5 minutes into a new "gig" and I had a black eye! She was a nasty, mean woman. He was content to sit in his recliner in his adult diaper and drink beer all day (except I wasn't ALLOWED to serve alcohol to either of them). They fought like 2 cats in a bag. I quit that day. One week later, they were back in the ALF he in a smaller studio and she in a more secure facility. The family simply couldn't keep them together, because she became so abusive. That's a switch up on your situation, but it was necessary to keep them both safe. Yep, it was about twice as expensive and I remember the daughter bemoaning how much this was costing and how it was cutting into her "inheritance".