When expressing that, referring to people, it could use a range of words, adjectives, verbs and related expressions.
Often they use something like "not a grown-up", crybaby, pampered, spoiled brat/child, fool, infantilized adult children and all that jazz...
Or, for instance something a la "he is not quite a grown-up yet.../isn´t a real man/acts like a boy" (or not like a emotional grown-up, if you wish).
And the Daily Mail online said that about Dad Brad and ex-wife Jolie:
...one might hope these two demi-adults would try harder
to be good parents and keep their complicated family unit intact. Apparently not.http://www.dailymail.co.uk/femail/artic ... ew-up.html
Well, that´s just an example, one knows that the UK tabloids can be harsh sometimes, or at least give someone a hard time!