Why is making friends as an adult so difficult?

M, 31 here.

Does everyone have friends? Other than my partner, I don't have any friends.

Not sure if i smell, or maybe I'm boring, or lack interests and hobbies. But it seems i really struggle to make friends as an adult. I don't have any social media (FB, insta, snap etc), so yes, that will probs make it very difficult to maintain friendships.

I haven't maintained any friendships from school. I might create some 'friendships' with colleagues whilst seeing them all the time, but those relationships always fizzle after moving onto other jobs. I thought i made some friends when i went back to uni few years ago, but that all fizzed out too.

I get it. Everyone's busy. Everyone probably has their own friends and not looking to expand their social circles. Even on my days off, i just want to be a recluse sometimes. But it would be nice to have a few people or a group of people to come over and play drinking games or whatever at times.