I keep getting surprised that the divorce rate is declining

I think the "cannot afford to marry" argument for the very poor is that the income requirements are so low for many government programs that if the couple were to marry, their combined income would disqualify them, even if neither earns very much money. But beyond that, I think marrying, in its conventional form, is a statement of optimism about the future. While some people don't marry because they think it's unnecessary or even harmful to their relationship or because they're radical feminists, most people still hold marriage up as some sort of ideal. It signals your arrival as a self-sufficient adult and carries all sorts of social signifying to it. In a weird inverse, if you can't meet that ideal - if you think you'll never be able to afford your own place or you fight a lot with your SO (and if you have money problems, chances are much higher that you will) or fill-in-the-blank pessimistic vision of the future - you may even think that you shouldn't marry or can't marry or don't deserve to marry. I think there is a weird thing going on where the over-idealization of marriage into something it's never been is contributing to its declining popularity. No one can meet that ideal, so why bother?