Comment by pembrook

Except you do not provide it for free. You provide it under the implicit transaction of your relationship, where you are both giving up value in other to get value.

Try betraying your partners trust and cheating on them - or refuse to take care of your children. They will likely be upset that you aren't holding up your end of the bargain.

Just because you haven't placed a price tag on your relationship and hate the idea of thinking of it that way due to modern cultural ideas of romantic love, doesn't mean relationships are not a transaction (historically in fact they did carry a price tag).