How is it possible for someone who enjoys being alone to feel lonely?

I'm a loner, most of my life i have a very limited friend circle and most of them have slipped away as the time and situation changed. It's quite obvious to say in the elephant in the room but it's just how I am. I'm an avid thinker, a great listener and empathetic.
How is it possible for someone who enjoys being alone to feel lonely?
Post Opinion