I'm in my late 30s, and I have found that making friends is different, but not necessarily harder. If you're still thinking back to high school/college days where you had "the boys" or "the girls," that's just not realistic. People have jobs, hopefully careers, spouses, kids. If your primary focus is on exclusive friend time in your 30s, that is very difficult to find. Most people have more than just friends going on in their lives--unlike in high school and college, where people typically had friends going on and lives that wrapped around it.
I'm fairly affable and outgoing, which helps, but I enjoy making friends with people that aren't. It's easier, and the best friends I've made over the last few years are people that aren't very outgoing, but they like being around and hanging out with an outgoing person. But that does mean that I'm usually the one to strike up conversation, ask for a number, drag them out when I've got free time, etc. To be honest, many of these friends don't necessarily make it easy to socialize with them, because it takes them out of their comfort zone. I'm aware of that, so I don't mind the extra prodding and encouragement that it takes, but I think if you're more like that, the best thing you can do is just try to decrease the amount of drag you add to trying to be friends (even though you might be unaware that you're adding that "drag"). Often people will just be like "ok. They don't want to hang," and they'll move on. I just grew up with friends that were always kind of like that, so I just know they tend to need a little more love and encouragement.
Beyond that, just prioritize friendship maintenance. Text people periodically, see how they're doing, etc. Friends are like plants: when they're new, they require a lot of watering and maintenance, once they're established, they require less. But you can't expect a new plant to take well to the treatment of an established plant with deep roots. You've gotta nurture it.
I'm often worried that I'm coming across too needy or bothersome whenever I'm reaching out, especially since people have much more going on in their lives than just friendships. Yeah it's difficult as adults ☹️
Well, when you reach out, are you in need of something? Sometimes it's just and being like, "what up, fool," or sending a meme that reminds of them or whatever. If you're only ever reaching out because ultimately you want attention, time, etc, maybe that comes off as needy (though I think that's ok too!), but sometimes reaching out is just, like, "hey, thought of you, I don't need anything!"
Learned this lesson as well as I'm approaching 30. Friendship just won't automatically happen anymore. It requires your effort and also your friends effort. If you don't maintain it, it will eventually die down because people are busy and move on with their life.
It will automatically happen if you have shared social space. However that shared social space isn’t automatic like it was when we were kids in school. In school we had a little community and we were there every day. In adult life all we automatically have like that is the workplace. (And of course people are pushing for more and more remote because who needs mental health)
So yeah. The most valuable effort isn’t so much to reach out and try to spark friendship, but to get off your butt and go to that weekly game night.
I will say that when I joined a league soccer team I had instant friends. Sports are amazing for that.
I'm just happy to have someone to meet online once every few weeks and play a game with, maybe to the pub once every two or three months for a pint or two.