Nothing is forever?

So my brother John is the only sibling i am close with.  We are the only 2 of the 4 kids that shares the same blood from mom and dad.  He has always been very supportive of me, and me of him.  My rock.  He is the brother that everyone wishes they had.  Smart, sarcastic, loving and supportive. 

When John and Julie got married I was thrilled.  Sad that i didn't get to go to the wedding (that is a whole diff/ story) but so happy that he found a grounded, educated, beautiful woman to take care of and be taken care of by.  They suffered the loss of their first born son during childbirth but moved forward to have 2 of the most beautiful amazing girls.  My Molly and Abby are like my first children.  I love them and would do anything for them.  I have a special bond with them that is so amazing.

I don't know all the details yet, but I just got some very heartbreaking news by text that John and Julie are splitting up.  I don't know what exactly that means, but it breaks my heart.  They are the only picture I have of a normal, respectful relationship.  Yes my grandparents were married 63 years, but I wasn't raised around them.  Before I met Rashad I would look at John and Julie and think, I hope I can make a marriage work as well as they do. 

This is so not about me, but I feel confused and sad.  Did I miss something?  I know I don't live in their house or bear the stress they do, but what happened?  I worry so much for my Molly and Abby.  The girls are so in love with their mom and dad.  I am so worried about their hurt and pain right now.  I don't even know if they have told the girls. 

I hope they are splitting up and going to counseling or something.  I hope it isn't the end.  I love my sister and am so sad to think that we won't have that family nucleus anymore.  And my brother is so sensitive.  I hope he is holding it together.  He had just booked a trip to Ireland for them and I was going to keep the girls for the week.  Was that a last ditch effort to make their marriage work?  This June they will have been married for 13 years.