Its a dreadful thing to occur because psychologically it can make him debilitating and insecure. I have a ton of friends and still feel that i am alone most of the times. Just because a person has loads of people for company doesn’t always mean he is not a loner. In fact he might still feel lonely because those people are not the people who are with you all the time. Apart from siblings who stay in the same residence as you there is no other person who will always be present with you. So with this in mind its fair to say that in-spite of having friends/companions a person can sometimes feel he has no one to be around with. This also leads to a state of depression and withdrawal. So best way to combat this is to keep the flow of activities going to distract you and also believe that in this world there is always someone to support you apart from your family.