While the Cavalier King Charles Spaniel is a sociable and people-oriented breed that thrives on human companionship, they can be trained to be left alone for short periods of time. However, they are not a breed that should be left alone for long periods on a regular basis. Cavaliers are prone to developing separation anxiety if left alone for extended periods, which can lead to destructive behavior, excessive barking, and other behavioral issues. To prevent this, it's best to gradually acclimate your Cavalier to being alone and provide them with plenty of mental and physical stimulation when you are home. If you need to leave your Cavalier alone for an extended period, it's best to make arrangements for someone to check on them, such as a dog walker or pet sitter. Alternatively, you can consider enrolling them in doggy daycare, where they can socialize with other dogs and receive plenty of attention and exercise while you are away.