Generally no one is surprised when a break up occurs amongst friends. Tell tell signs are evident. They usually start at gatherings. Once the overly PDA couple, they now inhibit separate corners. Women find it hard to not vent to girlfriends. Men usually just start hanging with the guys more often. Dreading going home, they hit more happy hours and start volunteering to work overtime.
Finally, an announcement is made. The news spreads faster than a viral video. A break up is not only hard on the couple, the friends are affected as well. My words of advise? Open your ears and close your mouth. Become an information silo. It is your job as a friend to be a shoulder to cry on as well as a sounding board. It is not your job to become Wendy Williams or Dear Abby. It is hard to emerge post break up unscathed. If you are asked how she is handling the ordeal your response should be, "She is disappointed but doing well." Omit the late night phone call to accompany her on a stalking exposition to which you declined and talked her off the ledge. Be an ear not an advise columnist. If you are asked for your opinion, at this time and not before, are you allowed to give it. She is not required to take your advise and most likely will not. Do not take it personally.
Distribution of mutual friends is often more difficult than deciding child custody. It would be much easier if a judge was able to rule on this matter as well. "It is herein stated that the plaintiff shall attend all Fourth of July boat parties, baby showers and New Year's Eve parties in odd numbered years." Since this is not the case, the friends are left with the dreadful duty of deciding who to invite to which functions. If you are equal friends to each party I would advise to invite both and inform them that their ex has been invited as well. You can now base future invitations on the maturity level at the event. You can usually count on one of them to get embarrassingly inebriated to the point of them deciding to "sit down somewhere" or not be surprised their invitations have been revoked until future notice.
Longevity of friendship is the easiest factor to determine who inherits the friends in a breakup. It is a good idea to be cordial to a new boyfriend or husband of a friend or vice versa. It is, however, common sense to avoid becoming super close just based on the sheer reason of current divorce statistics. Friendships become strained when you remain friends with the other party during a breakup. If I divorce him, so do you!
If you are going through break up or divorce, staying at home for the first month with a glass of wine is the way to go. This will save you the embarrassment of drunk texts or inadvisable hook ups. Go easy on your friends. This is an uncomfortable situation for them as well.