This is most evident when it comes down to group events, where you sometimes have to choose who to invite and who not to, while not showing any favoritism to either. When it’s totally unavoidable, you just have to give a friendly warning to both of them like, “Hey, your ex is gonna be there too?” But in cases where the break up is bad, the friends usually get divvied up into their original piles of “his” and “hers.”