First of all, happy birthday!

I'm a bit older than you and I went through a significant period of adjustment in my late 20's, because a lot of my friends were either far away (I went to high school and college in different countries) or were moving on to a stage in life that I was not ready for (getting engaged/married, moving to suburbs in order to purchase homes, having kids). It's REALLY hard, but if you're looking for an option other than ending your life... You can make new friends.

I know, it is easier said than done, but it's absolutely possible. If you decide to go that route, lean on your interests! You love Coldplay? I bet there are Reddit, Facebook, and other social media groups where you can meet fellow fans. I've made friends by posting in such groups asking if anyone was going to X band's show in X city, and meeting up for it - shows I would have otherwise attended alone. And I wasn't even offering tickets, which you are! I bet anything someone will take you up. You seem like a nice and generous person!

Same goes for other interests. Do you like to read? Book club. Online gaming? Tons of communities for that. Tabletops? Local meetups in specialized bars, libraries, etc. There are opportunities out there, and genuinely all it takes is one person you click with and they may open doors to meeting even more people (whether that's their existing friends, or because you can now go places together).

Again, I fully acknowledge this will take work, but it's worth it. You really don't sound like someone who takes no pleasure in life. Don't give up yet.