there's a big difference in "being alone" and "lonely" the former is more like a welcome solitude; "me time" so to speak where you know its not really how you wish to be forever more like a temporally break from human disturbances which you can fill up doing stuff you would normally not do when in company. However "lonely" is different. This is emotionally more a negative state which one doesn't really want to be in and where you actually crave "specific" company.Its possible even to be among hundreds and still feel "lonely" and loneliness is often linked to depression.
Personally I've been through both and whilst I appreciate my "Me time" I seek refuge in God from being "lonely"..this is never a feeling I want to ever experience again..Aameen!