My partner believes he is never wrong and gets angry when you say he is. How would you handle?

Age? Diagnosis? History of mental illness?

We honestly need more. It seems you have no question here, really. And certainly we can be of no help with answers for you without solid information of age, medical and mental history, and whether or not you are his POA.

You do tell us in your profile that your partner is 72. But there is little else to guide us.
Offhand, just from description you are talking of mental illness or dementia of a sort of FTD or Lewy's type. But that is pure guesswork.

Please tell us what you have done to get your partner diagnosed. If you have done nothing, then Geaton is CORRECT absolutely. Call 911 and have him transported to the ER. Call in Social Workers at once and tell them what you have told us and that he is not currently diagnosed but that he presents a "danger to self and others". If this doesn't work, time to call APS.

From your profile:

"My boyfriend is 72 years old. He started seeing things in videos that are not there. He gets mad and jealous and accuses me of certain things. That have not happened. Now he keeps forgetting stuff, if he goes out of the room to get something he forgets what it was. I'm talking all day long. At least 15 times a day. And can never remember were he puts stuff. If you try to tell him something is wrong he gets very angry and screams at you. I just need help figuring out what's wrong with him. Oh and he had his prostate removed about 6 months ago"

The very next time he starts screaming and hallucinating call 911. Tell them he is hallucinating and delusional and may have a UTI or some other problem and his behavior towards you is threatening and scary. They will take him to the ER and hopefully try to figure out medically what is going on. If they don't find anything, do not retrieve him from the hospital. Tell them he is an unsafe discharge. Then ask to speak to a hospital social worker. He may need to have a psych hold for a while.

Does he take any meds? Is it possible he is over- or under-dosing himself on something (even legal, prescription)? If you find any pills in his house you need to tell the EMTs or ER docs.

Kcrazy
Who is 28 yrs old? Look at your bio and see if it is correct.
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If he had his prostate removed 6 months ago and is now hallucinating, perhaps he has an infection. Did all this begin after the surgery? He needs to see his doctor for tests to see what is going on. Urinary tract infections can be toxic.

If you don’t know the medical cause of the behaviors, he needs a complete medical evaluation to determine what’s going on and devise a treatment plan. There are medications that can help to calm anger and paranoia. If there’s a dementia diagnosis, please don’t tell him he’s wrong, for his brain has lost the ability to reason and process that appropriately.

This sounds like a serious situation but I really don't know what you are referring to and can't offer much advice.

Does this person have mental illness and/or dementia? If so, don't bother telling them that they're wrong. You know they are so leave it at that.

If they are violent, cut contact so you are safe.

Can you please provide more information about this situation so that we can answer your concerns.