It's not easy to be alone. Some people do enjoy it, but it's rare. The best thing about being alone is that you don't have to give no one explanations for the things we do. We can be a little free that way. The bad thing is that we do not have any one to share our good times with. When one gets really happy, one wants to tell the world about it, but sadly there would be no one.
The people who are comfortable being alone, usually are introverted individuals. Meaning that they live in their own world inside their heads, and therefore do not feel the need to be around anyone. They would deny it, but deep inside they long for company, but not just any company though. Somebody who complements their personality.
Extroverts do feel a great need for company. They feel the need to share everything with everybody, or most. They enjoy being in groups. They tend to feel lonely quicker than introvert do. They seek for company as they are pleased when surrounded by people.
Whether an introvert or extrovert, humans are social individuals.