How/why do you think a person can be lonely around others?

I agree with Brandon that people can feel lonely with other people. For instance, many couples around me talked to me about feeling lonely even though they have girl friend or boy friend. Their major reasons were lack of communication, display of affection and misunderstandings. I think the most important cause of loneliness is lack of communication. Even though you are surrounded by many people, you may feel lonely when you are reluctant to approach to someone or when others don't really communicate with you. In this case, you are likely to feel lonely. Even if you are physically with other people, you don't feel like it, and feel aloof.

Another reason can be, as Brandon said, lack of understanding between people. Since you lived in different places with different people, you tend to have distinguished characteristics of beliefs. However, when those ideas are different from others, you may feel lonely, especially when there is no one that supports your idea. In this case, you have to fight alone for your ideas.

Even if a person is always surounded by many people, if the person does not share a single common thing with others, the person can feel lonely. Also, if you're just stuck in a situation where you must stay, you'll feel the need to go back to your own place and not want to be there. I guess uou can be lonely around others

True, when someone feels like they can't connect with other people, they can feel lonely, even though they are surrounded by so many people. It's about connection, sense of belonging to other people, when you don't have that, you can feel lonely.

If people cannot find anything similar or anything that they can relate to others, then I think that it will be difficult for people to be with others. People can talk about something only with they have something to talk about. A topic that would bring the people's attention to them, something that other people would agree about. These kind of things can be sources of people's interest and something that will bring attention to others. 

I think that everyone would feel loneliness in around other people if they don't understand and have sympathy to each other. For example, you can't be close friend and hang out with everyone, because maybe you and them don't share the same idea or taste of humor. Thus, if you hang out in such case, I think you will be bored and lonely.

The person can feel lonely if that person has quite and timid personality. When people who are sociable try to approach him to build friendship with him, he can avoid them or say something rude that will shoo them away. This may lead to that person being lonely.

I also think that a person can still feel lonely even though they are always surrounded by people. This might be because you sometimes feel like all the people are just full of fake sides. You might have people around you who you think that you are not really close to them.