I think “immaturity” is needing or expecting your physical and emotional needs to be met by someone else.
This is completely understandable if you are a child or a young adult. And in fact is essential at those stages in life. When you are young and inexperienced you may not have the capability to meet your own physical and emotional needs.
As you get older, maturity comes with the realisation that you have to take responsibility for yourself. Your physical needs are an obvious one, and most able-people achieve physical maturity. However, there seems to be some people that never quite reach emotional maturity. Or at least it takes much longer.
Emotional immaturity (by my definition) is when you have needs that aren’t met, which then result in pain. And you have no idea how to alleviate your own pain, so you project it out onto others. Sometimes in a frenzy trying to get them to do something you need or behave in a way that you expect. Eckhart Tolle calls it the “pain body”.
I have (am) working hard to identify and grow my pain body. I want to own my pain and find ways to meet my needs myself. This isn’t so much supercilious as it is lazy, because I figured I was putting a lot of effort in to trying to get what I wanted/needed elsewhere and failing. People generally don’t do what you want or expect them to.
A first step is to identify when something is my problem that I am projecting and actually trying to make someone else’s problem. A hint is when I realise I “want” someone else to do something, or for them to “change” something.
Don’t get me wrong, I’m not suggesting every man is an island. There are times when I have emotional needs that I want to share and fulfil via someone else, but with maturity comes some discernment and empathy as to when and how that is appropriate. It might also come with some noticing when it happens and checking in that it’s ok with the other person.
Once you start noticing in yourself it becomes easier to see in others. And once you start owning your own emotional needs, it becomes easier to start allowing others to own theirs. But don’t expect they will like it. Some people aren’t ready to own their own shit and always want it to be your problem. Under such circumstances, there’s a chance you will lose a good mate or two. That loss isn’t yours to control. So long as you remain willing to be their friend, you can’t control their withdrawal. You can only love and try to understand.