Why do relationships break?

It has been now more than 12 years that I know my wife, we married 2,5 years ago. Now since Thursday night 10th Dec. it seems to be over...

Can you imagine that a person you seemed to knew very well turns out beeing someone you have never known... I thought that this could have never happened to me but it did.

As I am reacting more rational and not emotional I tried to understand the reasons and asked her for a fair discussion - which we had but during that discussion I made an error and tried to discuss and pick up the arguments, qualify and give proper answers to them or at least to understand who did something wrong with this - this was absolutely wrong.

You never get through to someone with such an approach as that person has taken an emotional decision based on butterflies she currently has (regardless why) but she is already on a train not knowing if there will be service on board, if the compartments are comfortable, if there are any stops inbetween, if the final destination will be the destination she wanted to go to - I am trying to reach that train but it seems that I am loosing speed now as there seems almost no chance to reach it now.

I also gave the critisism some further thinking and came to the conclusion that most of the raised so called "facts" were just excuses to hide herself from the real reasons - and here I have serious doubts if she is not hiding herself from some other serious problems.

I decided not to run after her, will wait but not for ever.