It happened. The last straw that the two of you had to carry has broken the camel's back. The camel,  your straw, and all the pieces of your broken heart are scattered all over the ground. You don't know exactly how it happened, or even when, but as this particular argument wears on, you realize there is no going back this time. C'est fini. It's finished.

Now what?

Well, now you tell each other it's finished.

I know you think it's obvious. I know you think you did. But screaming “I'm done!” in the middle of an  argument that was blown way out of proportion five days ago is not “having the break-up talk.” It is getting pissed off and screaming something that neither of you is sure you mean, like a five-year-old who can't have dessert because he didn't clean up his room. And while not everyone in the world who is in a committed relationship is a mature adult, you claim to be, so how's about we do this right?

First, make sure this is what you want to do. There are a whole lot of reasons to break up in the wrong relationship, and even more reasons not to in the right one. How bad is the “problem”? And is there really no solution, or are you just too angry to see it?

Take a step back, and consider your options. Have a civil conversation with your partner about what ever it is you're arguing about. If this means waiting a day or two until you've both calmed down enough to be rational, then wait.

If it really is the end, in the words of the great Wil Wheaton, “Don't be a dick.”

Don't pick each other apart. Don't call each other names. Don't play the blame game. Don't try to pinpoint the reason you're breaking up. Despite all the fights you can recount from memory, and all the “wrongs” you did to each other, the reason is you're not meant to be in a committed relationship with this person.

This is not something either of you caused on your own. It's probably not something either of you caused at all. While some of us like to believe that if we were all “enlightened”, we'd all be the best of friends, the reality is some people don't work well together. Some people are better friends than lovers. Some personalities clash. We can't all be in love with each other all of the time.

Plus, if you handle the break up well, you'll both feel better about it once the initial hurt of losing a lover wears off. And who knows? Once you begin to recognize the fact that the two of you just weren't meant to be, maybe you'll be able to remain friends.

Handle any difficult decisions with as much grace as you can muster. Share custody of a pet. Let the person for whom moving would be the most difficult keep the apartment. Sell the house or car, and split the money. Whatever it is, while it's tempting to be selfish, do what's best for everyone involved, not just what would make you feel better.

But above all, don't beat yourself up over it, no matter how it goes. Sometimes, life throws a wrench in your plans. Sometimes, there's nothing you can do about it.