Guinea Pigs are incredibly sociable animals and in the wild they would live in large family groups. They are happier and healthier living in groups. They would never choose to live on their own. Therefore it is very unnatural for them to live alone without the company of other guinea pigs.
Keeping a solitary guinea pig is cruel, however much human contact he or she may have. This contact is not the same as the contact it would have from other guinea pigs. Imagine, would you be happy just living with guinea pigs, and never seeing another human?
Just like us guinea pigs need to be with someone who speaks the same language and enjoys the same things. Even if this is a bit of a squabble over a carrot, a snuggle at bed time, or a chase around the garden. Guinea pigs are much happier when they are with other piggies. They are more content, confident and happy. It will not affect how friendly they are with you, or make them less attached to you, if anything it will improve a guinea pigs relationship with humans, as they are happier.
It is the same with keeping a guinea pig and a rabbit together. They may like each other and appear to get on well, but they would never pair up like this naturally in the wild. They would group with their own species. Again they have very different needs and behaviours, which can only be satisfied by another animal of the same species.
People with one guinea pig will often say their piggy is happy and content. But they have no comparison as to how happy and different guinea pigs with other guinea pigs look, and how different their guinea pig might be if they were with another guinea pig. I have re-homed guinea pigs to live with guinea pigs that have been solitary and owners have commented on the huge difference it has made to their guinea pig. Some have said they didn’t know their guinea pig could speak before, they have never seen their guinea pig look so happy and excited, and that their guinea pig is far more active and interested in life.
Some people say they have a piggy that does not like other piggies. There is the odd piggy that doesn’t but this is not the norm. You may have had a guinea pig that didn’t get on with another piggy; this is usually a clash of personalities. There will probably be a piggy somewhere that will get on with yours. It makes no difference if they have not been kept with piggies for a while, they will still enjoy the company of another piggy. Even if your piggy won’t tolerate another guinea pig in its house, it would still benefit from being near another guinea pig, even if it is separated by a partition.
If you have a single piggy please consider finding a friend for them. I can help support this process and find a companion that will be suitable for your guinea pig.