Can dementia be a part of extreme grief from losing a spouse?

Yes, if someone is at the beginning states of dementia, losing a spouse is a major change in their routine. Or it could be your Dad-in-law is very angry at his wife for leaving him by himself. That probably wasn't how he had envisioned his future.

I know my Dad [94] was very upset that my Mom [98] had passed as she could have still been here if she wasn't so stubborn and would have welcomed caregivers into their house to house to help.

I remember a few days after Mom had passed, Dad asked me to remove all her clothing from the house, which I did. Dad was finally able to move to Independent Living, which I believe he wanted to do years earlier but I guess my Mom refused to move.... the house was just too much for him to maintain and Mom was still having him climbing ladders in his 90's. He misses my Mom a lot, but doesn't miss that house.

They have a large cattle ranch and up until my MIL got ALS they worked the ranch together as they have for 61 years. Then my FIL became her caregiver. He took care of her day and night from Nov. 2014 til Oct. 2016. We are at a total loss as how to get him some help. It is very evident he is not thinking clearly and the anger gets worse and worse. Any suggestions would be most welcome. Thank you.

its common knowlege in relationship phsycology that partners prop up each other . when one has a phsycotic break , somewhere , a partner is flipping out too .

It sounds like there was some kind of break with reality after she died, as it also seems as though he was devoted to her and they worked together as real partners. It might be that denial is his way of attempting to cope - denying that she was faithful would lessen the impact of his grief.

Apparently anything reminding him of her is being destroyed to wipe out the memories that are triggered by her possessions.

This is really sad, and I think a bit extreme, but I'm obviously not aware of the scope of reactions when one partner dies.

If he's religious, I would ask the paster/minister/priest/rabbi to counsel him. If not, are there any others in the family, or close friends (especially someone who's also lost a partner) who could spend some time with him?

Funeral homes sometimes have grief counseling. You might check with the home that handled her funeral to see if they do.

Hospitals and I believe nursing homes also sometimes have grief support groups.

I'm sorry your father is reacting so extremely; this must be very hard on him to accept that she's gone. Perhaps you could offer to help him clean out her things, if there are any left, and just take them home with you or put them in a storage unit if there are things you want to save.

Another aspect that bothers me is if he comes back to reality and realizes what he's done, that he's destroyed evidence of her existence, that he'll become overwhelmingly depressed and despondent. You might want to prepare for that.

If you know of a psychologist, it wouldn't hurt to have a consult, probably more helpful for as you are open to advice whereas your father probably isn't.

He has moved from Shock , past Fear, and is now stuck in Anger. Anger can take any direction, no one is safe from it. Next step is Despair. Maybe in a year or so he will get to Acceptance.
My mother died at age 37. Dad was angry with her for leaving him with 4 girls. About every 3 months he would fly in to a rage directed at us.
He was still angry when he died, 38 years later.

Kate, I just thought of something else... there are the "what ifs". Your Dad could be angry at himself thinking he could have done more and maybe had prevented your Mom from getting ALS, etc.

My Dad is still going down that path, convinced that if their new primary doctor had seen my Mom, she would still be with us today. I just cannot convince my Dad that it was a series of falls, with serious complications from head trauma that took Mom, and that no doctor would have been able to correct.

Thank you to everyone who responded to my question. I really appreciate the feed back and you've given us many new ideas and tips with your helpful insights.

There are lots of expressions of grief including pseudo dementia, I should know I was dxd with it. It turned out it was an episode of significant situational depression. Get Pop off to a geriatric psychiatrist to figure out what's really going on and then either meds or counseling. Yah, I'm sure he won't want to go, but it's necessary.