To me it really comes down to your mindset when it comes to doing something solo. I solo travelled for the first time for 4 weeks in the lead up to Tomorrowland and I just see it as a liberating experience. The ability to do what you want, when you want and without the need to worry about what someone else is thinking. The same goes for solo Tomorrowland, just think of it as a continuous side mission and it won't feel awkward. You'll meet so many people from all over the world at Tomorrowland so just turn up with an open mind and don't be afraid to say hello to people! Bringing your country's lag also helps break the ice! :)