Lonely inhabits a space of self-dislike, self-hatred, self-confusion, self-diffidence, pretense, fear, sadness, DISCONNECTION…so much disconnection, often, with oneself, a feeling of exile, a feeling of not belonging, a feeling of punishment, a feeling of “other”, of being weird, of aching, of being devoid of something, of lack. So much lack. You cannot be lonely without lack.
Alone is quite literally…with self. And only self. And it DOES NOT have to imply the former, the loneliness…the lack of self-worth, connection to others. Being alone does not imply that you are weird or sad or pitiable or less worthy. Alone is an opportunity to recharge (and be naked, as you expected me to point out), to play Solitaire, to connect with self. You cannot be alone with another person.
You can be lonely with another person, with other people.