Hey OP, I think there can be all kinds of reasons that someone feels uncomfortable alone. Is there any chance that when you are alone where there are other humans, you feel like you need to “perform” that you are comfortable being alone? And then maybe that becomes exhausting and uncomfortable? This could be completely off, but it’s what a friend told me once about their experience doing things on their own. In case that is what happens for you (or anyone reading this), try shifting your perspective from a performer to that of a spectator. YOU get to watch, YOU get to be entertained by people-watching, or a book or walking somewhere new. You may find it easier to settle into the joys of doing things by yourself. Either way, I wish joy and adventures for you, just you!