Why do so many people cheat?  For several reasons - and I can talk about why they do on a cultural level, on a developmental level, and why it doesn't have to mean the end of the marriage.

Why do people stay?  Sometimes an affair is a wake up call in the marriage.  It can shake the very foundations of a relationship, and many times that may be what it takes for a couple to pay attention and start working on their marriage or partnership.

Why would a woman stay with a husband who has cheated, particularly if he is in the public eye?  Just because someone betrays you doesn't mean you stop loving them.  Couples can move past forgiveness to a "new monogamy" and that can mean a new future to a relationship.

How does Hollywood mirror our everyday relationships, or does it?  Hollywood couples are under a microscope, and the pressure of constant scrutiny makes their behavior seem different than the rest of us.  But is it?  Or are they just acting out in the same ways the rest of us do?  If you had paparazzi following you around,  what would you get caught doing?