It is a knee-jerk reaction sorta question - I get that. They find out you are divorced and then out comes the question of "So sorry. What happened?" However, I would imagine that many people would understand that they are not going to get the whole story. Some things are just very personal and hard to explain to a person whether they were a family member, close friend, or acquaintance. It seems though, that no matter what you say to that question - you can't win.
The reason you cannot win is because the whole situation is a failure - right? Unless the person was physically abusive, there just never seems to be a good answer. Everything that comes out of your mouth will be judged against what that person thinks about marriage. It is not anything against the concerned party but just the way it goes. Whether they are currently married, were, or idealize it from a far - it just seems that more times than not, the choice to divorce will be seen as some breakdown and failure.
Walking around with that feeling of being a failure or broken drove me crazy. When the question came at me and I answered with "things were not working and we were not happy anymore. We are still friends and it's for the best." (Of course, there is more to it than that but you have to find a basic response in order to sum it up in a nice neat package) After I responded, I still got that look like my dog died or something. No matter how good of a day I was having and confident in my decision I felt, it used to tear me up and it felt like someone just punched me in the stomach, yanked on my hair, and shoved my chest all at once. I had to grow a tougher skin about it all. Most importantly, I had to grow in my understanding of others and that their reaction was theirs based on things they believe and know about the world from their up bringing and life experiences. Also, they were not married to him or to me. One can never know what it is like in someone elses home, relationship, head, or heart.
Difficulties were in telling family members and closest friends of our choice to move on with the divorce. We had been the couple and such good friends for so long that nobody understood. How could they though? There are things that you just don't talk about at family/friendly gatherings. Personal things between us that only we had buried within and carried around. Since we had been going through it for a while and living it, we had more time to process our decision and everyone else was left stunned. They wanted to help and believe things would be worked out. However, they soon realized that we had already gone through those stages without them knowing or being involved. I remember telling my dad "...sorry that I am not at a place of needing your advice but rather in a place of needing your support. Unconditionally."
Support is something that is greatly needed during such a major life changing time. It is a simply complex request one might say. Not only did my family come around with their support, best they knew how at the time, but my friends were a huge lifeline for me and still are beyond any thanks I could ever give them. But I cannot forget to mention that my Ex was a huge support too. We have been helping each other out through things as well and it just goes to show how we can still care about one another but not be for one another as life partners. We are moving forward and are trying to forgive ourselves for the what happened in it all.