[MiddleEndian]

This is not necessarily true, beyond the fact that you must pay to live no matter what. If you have one person making, say, $300k/year and another making $60k/year, together you share a bedroom, share a fridge, share a stove, share a living room, etc. Your total costs could lower than they would be otherwise.

[akomtu]

Even if you're sharing the fridge, you still owe 120k/year. This amount is just due at divorce, which creates an illusion of saving money.