My suggestion is for this couple to seek out competent and qualified financial advice from a financial counselor or financial planner.
It’s easy for an individual to flippantly spend money they don’t go out and earn themselves. I can understand the OP’s concerns. If both spouses were working, the circumstances would be different. It’s often difficult for individuals to stay within a budget, and when people are used to being handed everything (first from their parents, and then from their chosson) and not working for it, they fail to learn the value of a dollar.