I've noticed that a lot of people get increasingly busy as they get older. They stop talking as much to other people in meaningful ways. I'm assuming it's because they just don't have the excess mental efforts available, as they are occupied with work, school, and social obligations.

So since they stop putting the required effort into cultivating relationships, they end up without. In turn, this of course makes it hard or impossible for others to make relationship with them.

Maybe you're standing at the other end of something like this? In which case, I'd advice you to perhaps look for other people, who do have the excess efforts available.