Sadly, one of my male guinea pigs died a couple of weeks ago. He was 4yrs old. I have one left, who is nearly 5. I don't know whether he will be happier on his own, or whether I should get a new friend for him. He seems o.k in himself, but I don't know if he would like guinea pig company. They had been together since they were a few months old, but were not brothers. These are the first ones I have had, so I have never been in this situation before.