Additionally, keeping only one guinea pig can lead to loneliness, boredom, and other behavioral problems. A solitary guinea pig may become more susceptible to stress and illness, have less active and less lively, and may start developing destructive behaviors like chewing the bars of their cage excessively.
If you plan to have just one guinea pig, you should be aware that a large part of your time every day should be allocated to be with it so it compensates its social needs of living on a colony or herd.