Before marriage: 175 I + 50 of consume (the man consumes 25 in the form of a clean home, his maid consumes 25 to buy shoes) = 225.
After marriage: 175I + 25 of consume (the 25 consumed by the wife to buy shoes) = 200.
By the way, your question is good, and I really wish HN wouldn't reflexively downvote stuff they don't agree with.
When they get married, the man's income stays the same. The woman's income evaporates. She's not getting paid anymore. So their combined income is now 200K.
But the situation is exactly the same! The same amount of work is being done.
GDP works exactly the same way. It's an account of money flows, not production or actual economic activity.
Again, you are looking at the GDP of the man, not of the pair of people.
Because the man first spends 25k, and then the maid spends 25k again, the 25k is counted twice in GDP statistics. In the second case, it is counted once.
This is why GDP != Income.