How did the coming of no-fault divorce change things?

Prior to the so-called liberalization of divorce, which began in 1970 in California, fault was the only way to end a marriage in many jurisdictions. That meant that the plaintiff-spouse alleging fault bore a heavy burden proving the facts underlying the allegation and withstanding the defendant’s trenuous opposition. Proving could turn on the corroborating testimony of witnesses; defending could mean claims that the plaintiff procured the adultery, or condoned it, or colluded with the defendant in the commission of the alleged acts that substantiated the fault.

For sure, the old divorce laws were far more restrictive, "demanding that the parties spend a good deal of their legal efforts toward proving the fault grounds." This means that the parties spent "much, if not more of their financial and emotional resources proving (or defending against) the grounds as they did on the part of the litigation concerning financial or child-related issues."

However, the proof of fault in the defendant "was used as a basis to mete out" punishment, "not only the amount of financial support awarded the aggrieved spouse, but also in deciding the quantum of property the court distributed between the parties."

Some people are nostalgic for the old days when people who were unfaithful had their fun and paid for it. Nostalgia is seldom the basis of a sound argument.