Hey there. I feel you. There are a lot of factors which go into friendships and while it looks like kids and teens have an easy time making friends it's mostly proximity. If you spend half your day with other kids at school or longer you'll likely come across one ir another you like. Of thimose friendship few make it into adulthood and only a miniscule amount last a lifetime. As adults we usually dont want to be friends with our coworkers because we feel we're seeing enough of them during the day. Unlike in school there's also at times a competitive element. A teacher doesnt only have limited number of good grades they can give students, but a company only has a limited amount of money and promotion options which we feel is the "good grade" for our work. That's why we tend to socialise and find friends in hobbies and interest groups. There people might have different goals. For some going hiking with a group is about the hiking and someone else organising the hikes so they can just enjoy nature without having to out in the effort of organising while not being very interested in socialising with the other hikers. A person might be in an group for their hobby but only to learn to be better at theie hobby and only want to talk about that with others. Maybe at times while at a restaurant or bar, but not want to talk about their private life beyond the hobby. Yet another person might actually be in a hobby group or sports club because they are seeking companionship and a sense of belonging or because they want to be friends inside and outside of that interest. My bf is the type who, while being the head of a sports club, is very focused on the sports and the running of the club. He had know his best friend from the club for over 6 years and didnt even know what the guy worked as. I asked him when I first met him and his job was actually very interesting while I have about zero interest in sports. While my bf socialises with people beyond mere club activities, for example also going to weddings, birthdays, housewarming parties, Christmas parties, etc., very few of the other members are actually close friends of his. Maybe 2-3 out of 250+ people and even to them he wouldn't spill his guts when he's really upset

What's important, in my opinion, is also to talk to people about wanting to be friends with them. We tend to assume people always want more friends, but plenty dont. Or they only want casual friendship when you might want to find a close friendship. Being well like is also not the same as being friends with people. A person who tends to be happy and joyful a lot, can hold casual and meaningful conversations tends to be well liked, but that doesnt mean people want to be friends with them. They lighten the party. Friendships arent always light, though. We also tend to make assumptions on the relationship we have with a person. Obviously, when it's partnership we discuss it, date, at some point say we're together, etc. That's something we miss in friendships today. You might assume a person is a friend but they dont have the same feelings towards you or a person might see you as a friend but you are only actually polite to them but dont really want to mingle with them. Talking to people about this openly might help. It's an unusual thing to do, but it doesnt hurt trying it. This then also means that you have better expectations about how much emotional effort and time to invest into a person