Simply by spending our "own" money and minding our "own" businesses actually is a way to avoid communication and in my opinion may sometimes lead to a bigger problem.
My own parents are like this, my mom comes from a rich family and is big spender; my dad on other hand is much more frugal, he tends to save and invest more. I think with proper communication, they could be good partners in terms of finances...but they chose to take care of their own finances and closed the communication channel. They could be better off if they understand the "synergy".
Oh well, I guess I learned their lessons:))