The GDP of a country is an annual indicator that counts the goods and services provided in a country (in one year).
Before the marriage: The butler provides a service to the woman a receives money as his payment. In this relationship (woman-employee) there is a service that is been provided which means that it counts in the annual GDP.
After the marriage: The butler who now is the husband, continues to wait on his wife but not as a woman-employee relationship but as a husband-wife relationship. This relationship only changes in what they are because the wife continues to support the husband. So, it doesn't make any sense if the GDP changes.
Something different would be if in one of the cases (before and after) exists payment and on the other one doesn't.
The answer to question 1: The service that is provided doesn't change, so the GDP shouldn't change either.
The answer to question 2: It shouldn't because there is still provided service.
The marriage would affect how the output in the economy is calculated by decreasing the labor strength of the economy as the butler is no longer a butler the husband of the woman who employed him.
Explanation:
In the given case, the output of the economy is very less likely to get affected as the butler and the woman have chosen to continue working in the same way they did before they got married. The only difference that would be recorded would thus be in the labor strength of the economy which would be observed to have decreased.