Aloneness is a noun that describes the physical state of having no one else (or no friends) present. Loneliness is a noun that describes the aching sadness one can suffer from feeling alone. The two are often conflated in modern society -- but they don't have to be.
It's easy to believe that our lives are too full for solitude. But the rewards of carving out time for yourself are great (just be careful that it doesn't feel like an obligation). Befriend yourself, and prioritize one-on-one time with that friend.
I've done something a few times over the past few months that I would never have dreamed over doing 10, five, or even two years ago. I've attended events completely stag. And let me tell you something, it ain't so bad.
Instead of focusing on what you don't have -- bring your awareness to what you do have. Friends, family, a job, your health, freedom to see whomever and do whatever you please, the ability to be of service, etc.