Someone made a shidduch and the parents of the chosson and kallah don’t want to pay shadchanis. The Kallah’s parents are not frum and don’t understand why they have to pay money. And the Chosson’s parents who are frum however simply don’t want to pay any money. Do the Chosson and Kallah have to pay themselves now?
No, they don’t have to pay, unless it was understood in advance that they would be paying.
Although some write that the basic obligation of paying shadchanus actually falls on the couple, the universal custom is that parents pay the shadchanus, and if nothing is said to the contrary, this is the only expectation of the shadchan.
If the parents fail to pay, this will not obligate the children to pay their debts. This is the ruling given by the Erech Shai (185).
Please see here, in the section entitled “Who Pays the Shadchan,” for more details.