Failing to live up to expectations
I've seen the movies and TV shows and have read the books.
I know that guys who, in the past, have shared drinks, drugs, friends, and song sometimes get back together for a little while, and I know how those reunions are supposed to go. The guys should take a vacation from their marriages, responsibilities, and restraint by coveting and sometimes even reliving those shared drinks, drugs, song, and friends, all the while bemoaning their having grown up. On rare, extreme occasions, one or more of these guys abandons his maturity to return to his past.
So when two of these types of guys get back together and reminisce about their history before launching into full-on, effusive praise of their current marriages, responsibilities, and restraint, pop culture says they're doing it wrong.