Because, once they are married, she is rich too....

Because the rich people have to marry who their parents choose since it is the parents who provide the wealth.

There was a popular TV show on the lines of 'Who wants to marry a millionaire' in which millionaires appeared to find wife from common folk.. 

Didn't Jack Ma merry a simple teacher ? ...when he himself was a simple teacher. But he is certainly in a position where he could trade her in for a prettier model. 

over the top healthy "rich" and sought after white guy escapes to marry a destitute 2 time divorcee with a daughter....  yes a daughter.... and lives to enjoy it

It happens, you just don't know anything about your country.