My 75 year old SO is now in a SNF and having wonderful care. She has improved physically and mentally immensely since being there. Now she is crying, begging, promising ANYTHING if I will just get her out and bring her home. On the other hand, she doesn't believe there is anything wrong with her that pain medication can't handle. We went through this exact same scenario 4 months ago. It took less than 2 days for her to refuse any meds except pain med. She says that now it would be different. Past performance says no. She accuses me of not caring any more, punishing her, wanting to get rid of her. That is no where near the truth. I am totally alone without her and I miss her terribly. How can I convince her she needs the care she is receiving.
Back when my loved one first went into assisted living, I would tell her that the doctor was monitoring her progress and that when she was to a certain point she would come home. I said that every time and she accepted it, but she would forget that explanation and ask a few minutes later. Eventually she forgot she had a home and hardly ever says that now. If she kept asking during my visit, I would try to redirect her by walking around the facility and asking her about various residents, looking at tv, walking outside, pointing out things in a magazine, sorting out her closet, anything to change her focus.
You have to learn to not allow the pleas to torment you. She had no more business living alone in her home than a 5 year-old child, but she couldn't see that. She said her neighbors could take care of her. She could not understand that her neighbors offered zero help to her. So, I had to insist that she stayed in a safe place where her meds were administered and she was well fed and cared for. It brought me great satisfaction, because I knew it the right thing to do and is she were in her right mind, she would know that too.
I know it's hard when she's begging you to take her home and I'm sure you must have a lump in your throat and tears in your eyes when you leave but you are doing the best you can for her. If you could care for her at home you would but you can't. Now all you can do is visit her and make sure she knows you love her.
As for convincing her that she needs the care she is receiving, sorry but one cannot convince a person with dementia of anything, all you can do is redirect the conversion to something else. Otherwise it will be a losing argument.
What I do with my Mom any time she asks to go home I will say "tomorrow".... I found using very short sentences and just one word is enough for her to understand and accept.
Please note you are doing THE best thing possible for your sig other having her in a skilled nursing facility, because with the Staff this isn't their first rodeo, they know what to do. Otherwise if your brought her home, you would need to hire skilled caregivers for around the clock care. And seeing her like that 24 hours a day would do damage to your own health.