family of 2 and family of 4

Can someone out there tell me how does marriage works?

Man marries women. They stay together alone, build a family.
Man use to pay everything back in the days during our parent’s time.
But these days, everything is equal… rite.
Fine. Split the bills….


Now…
Man marries women, they don’t live together.. they live with man’s family.
Does that means that the women have to bare a bit of the cost of living of 'the family'?

Or does she have to contribute the expenses of the family in terms of bills or food or the maid?

Or she does not have to cos, he has made a vow, when he made her his wife…. to take care of the women. And love the women, and blah blah blah….

Does the man have to pay the women monthly allowance when he marries the women or he does not have to since she’s working as well?
And on top of that they are staying with his family.

I wish thare’s a dummies for these things..