Why do some stay and others run for the hills?!

Taking a small break from my usual musings to wonder about this:-

This year seems to be the year for multiple affairs talking in particular about Tiger Woods, Jesse James and David Letterman.

As much as i would rather not read or watch all the sordid details of these families unraveling it is captivating. I think in part because it is scary.

It has made me wonder-
Why do some stay and work through the damage that infidelity brings, while others run as fast as they can!

Elin didn't immediately file for divorce, neither did David Letterman's wife... As we all know now Sandra has the papers in the works.

And this goes for men as well. Because women cheat too. As much as we would like to think only men cheat it happens both ways. And some men stay as well.

Could it be the history of the relationship that makes it stickier. Meaning that you want to stick with it. (Sorry for the making up of grammar LOL)
Could it be not wanting to loss a friend?
Could it be not wanting to break up the family?
Could it be afraid of the great unknown of single life?

I just wondered. As a teenager I have always thought I would be opened minded and I was not so opened minded with an old boyfriend who cheated, but I know that was because he did not come clean in the beginning. So may be that is the key. The truth must be forthcoming ! WHo knows?

Now that I am married I still think I would try to work it through. I guess the situation will have to present itself for you to really know how you would react.

What do you think? Why do some stay and some run as fast as they can? and what do you think you would do?