I don't know if it's "in stark contrast with the time of the year." A lot of people feel lonely around this period, because the holiday season and the festivities can shine a brutal spotlight on one's own lack of company. That's why it's easier to feel less alone when you're in the middle of nowhere, than when you're surrounded by hundreds of strangers.
I used to be like you, though at different times of the year. I never went to school proms, I skipped several field trips, I've never gone camping with friends, I've had maybe two sleepovers in my life and they were both with the same friend. It just always felt like my social life wasn't as rich and varied as it should have been.
Today, that's still the case. I don't really do much apart from work, sleep, and take care of household/family responsibilities. Or so I thought.
The world is a fucking big place, and life is fucking hard. Even those people who we envy for having big groups of friends, or for being in relationships all the time, or for celebrating holidays with fun parties...even they haven't got it all. In many cases, they're absolutely miserable despite their apparent lack of loneliness.
I've learned to enjoy the little things I have. I place great value on my free time, and I try not to let society dictate what a successful life looks like. Very often, the "model" structure isn't applicable to our own values and capabilities. Nor should it be.
If I manage to play video-games a couple of nights and go for a walk, I'd call that a good week. Parties? They're not all that, and if I get invited to one, then I can be happy about that. Field trips? I chose to save money on the fees and buy myself a camera instead. I still have that camera and it's given me hundreds of times more joy than three days on the Isle of Wight with a bunch of sweaty teenagers could've granted me. Relationships? Yeah, it sucks that I've never been in one. I think about that pretty often. But the right time will come, and I've matured and improved myself way more for being single this whole time.
A big part of it is just learning to relax and not get anxious over your fears about whether you're wasting your time. We could all be making slightly better use of our lives, but as long as we make an attempt, we don't need to beat ourselves up for not getting it right every single day.
You probably won't be able to change your mentality based on my writings alone. It's more complicated than that. It might take therapy, or it might take age. It might even take some trauma to help you (eventually) see something you missed before.
Life is constantly changing in ways we don't even notice. I firmly believe in a simple mantra: everything happens exactly as it needs to.
Call it destiny, God's plan, or cosmic determinism, it doesn't really matter. But there are no absolute failures and successes in life, just like there are no absolute rights and wrongs. They're all just shades of grey, and they all carry potential for learning and evolving.
OK, you didn't get to perform in that social function. Talk kindly to yourself about it. Why didn't you make it? Was there anything you could've done? What can you do the next time an opportunity like that appears? What were you able to do because you didn't participate in the function? What constructive meaning could this """failure""" have on your journey through life?
Try to see these events as having a purpose that extends beyond the moment and you'll unlock stronger reasons to keep living, and to keep trying. When you become aware of these long chains of cause and effect, that's when the beauty of life truly comes alive.
I can name one: hugging
~~God I'm so lonely~~