In my opinion, of course it is. It depends, maybe this teenager can't find anybody whom he/she find interesting to be friends with.
That would be weird.
It is the teenagers life if you start with no friend by the end they will have more friends then you will ever think
Everyone should have friends, even if just one. So, no this is not normal per say but can easily be fixed with a little creative tweaking here and there.
Well my step sister has none but she has her sister and she is outright mean and I think that is why