How to help cat grieving the "loss" of a human?

Question

My cat is grieving because my brother moved out.

My brother was the cats chosen human and even though he will cuddle and play with us others, their connection was special.

Since my brother moved away 2 weeks ago my cat has barely eaten, seems apathetic and does not go outside much.

How do we help him get over his "loss"? I checked out My cat is not eating or drinking anything after the death of the fellow cat, but the answers are mostly focusing on food and the loss of another cat and it is not what I am after.

So far we have been giving him extra attention and tried playing with him. We will take him to the vet this week to rule out any illness.

UPDATE: We went to the vet and the cat is dehydrated and lost 700g. They gave him an infusion and gave us a pheromone spray. So sickness is ruled out.

Answer 1

So I will post my experience with how we dealt with our cat as an answer. He is fine again.

Most importantly if this is happening to your cat and they do not drink or eat for an extended period of time you have to take them to the vet.

As I said our cat was lethargic and just not doing anything and there was no way for us to get him out of this state.

What we assume got him out was the visit to the vet which he hates with passion. That time he was even more angry than usual because of the infusion. He hissed and clawed and was completly out of it. When we took him back home he just went to being normal.

So I am not saying take your cat to a place they really hate and make them all angry. But maybe surprise them in a good way. If there is a place your cat really likes, an activity he likes but generally does not get to do, a very special treat or food that you can get or maybe just a person that does not belong to your household but the cat adores - go there, do it, give them or get them.

I hope this well help someone in the same situation. Just generally be there for your cat and support it as you would a grieving person.