Mother in law, who has dementia, gets extremely upset about being “left on her own” and is “sick of feeling lonely”. How do we combat this?

My mother is 87 I am a full ten years from Retiring. I work a standard 40 hours a week. My mom lives on her own, has friends, plays cards, talks to people on the phone almost every day. Her neighbors check on her constantly. She always has enough food, clothing etc and can afford the heat, rent etc. If I go visit her and need to wash my hands or go to the bathroom she will follow me to the sink or hover outside the bathroom door. A few years ago I had to take her to an out of state funeral. I was changing clothes and I could hear her asks 3 different people "where's _____" Finally I screamed "I'm in here changing my clothes". When I got done and came out. She looked at me and said "where were you", "I was changing my clothes" "Well you left me alone". I was gone about 5 minutes to change clothes. You can't combat this. it's something they just have to go through. The perception of "lonely" is different to them than you. I have started doing the following. Before I go to the bathroom if I am at her place "Mom I need to use the restroom, I will be right back". Sometimes this works sometimes it doesn't.

The short answer is no, you cannot change this behavior because she has no short-term memory anymore. Even if you could theoretically change this behavior, her ccognitive and physical/medical are needs will only increase and become more demanding and intense. What is your partner's plan? He needs to read the posts on this forum under the topic Burnout. Many have attempted to do what he is now doing, only for it to be a disaster.

Your MIL sounds like she would definitely qualify for MC in a facility. If money is the issue, he can apply for Medicaid for her. If he doesn't think she will qualify, then he should invest in a 1 hr consult with and elder law attorney who has experience with Medicaid who can provide professional and accurate guidance and strategies to qualify. You both can't go on like this. It is noble of him to attempt to be her full-time caregiver, but ultimately it might cost him his health and his relationship with you. Hopefully he is not financing any of her care. This is also very ill-advised. I wish you both wisdom as you move forward to change this situation for the better.

It certainly sounds like she is experiencing delusional thoughts. Is this a new behavior for her?

Have you mentioned it to her doctor? Maybe there are meds that could help her.

Profile states caring for Mother/MIL, 46 yrs, at home with age-related decline, alzheimer's/dementia, anxiety, depression, and hearing loss. Crickey! Is this age correct?

Sounds very stressful. She either needs a care companion or a memory care place.
He needs his life back, and to be with you.