Hello,
I appreciate the rewriting (I remember a previous version where everythin was too vague) but I think that this logline fail to tell the most important thing: 'what happens?' - where is the source of conflict?.
I pesonally don't like?sentences as "navigate the intricacies of their relationships" and "its likely there will be some casualties along the way", because they're too vague.
"The brotherhood is about to become the Fatherhood" is excellent for a teaser or tag line but in my opinion this kind of sentence have no reason to be in a logline.
It's very difficult o write loglines for 'low concept' movies, movies where everything is in the dialogues, characters and relationships. A way to package this kind of movies is to wrap the concept in a clear goal oriented structure, create an external and a clear source of conflict. Or at least confine the situation.
Something like:
"Turning 40 the same month, four longtimes friends struggle to keep their brotherhood alive under the pressure of becoming fathers".
I don't know if it's good, but what I tried to do is to build a starting point (the 40 bithday) and to suggest a conflict (friendship vs family). I think this can implies that "there will be some casualties along the way".