what the ****, some of the replies have been just simply retarded.
The only difference between a normal relationship and a celeberity relationship is that they look better on average.
Being good looking and a skilled actor, doesn't mean you understand anything about women or men. They have to marry other celeberities because they wouldn't be able to find any other person that wasn't starstruck for them.
They wouldn't be able to know if the person likes them for them, or for their fame, money, looks, etc. So they marry someone of equal porportions.