Source: H. Graetz, History of the Jews, volume II (Philadelphia: Jewish Publication Society of America, 1893) 238.
"Frivolity in the women and licentiousness in the men were so completely the order of the day that the most eminent teacher of morality of that time, Jochanan ben Zaccai, found himself obliged to abolish the ritual hitherto used in cases of suspicion of adultery."
Graetz is referring to Mishnah Sotah 9:9, which cites Hosea 4:14 as a proof-text: "I will not punish your daughters when they play the whore, nor your daughters-in-law when they commit adultery; for the men themselves go aside with whores, and sacrifice with temple prostitutes; thus a people without understanding comes to ruin" (NRSV). In a footnote, Herbert Danby mentions Gem. 47b, which states, "If ye yourselves are above reproach the water will put your wives to the proof; otherwise it will not put them to the proof."
The apostle Paul affirms that the law was given for transgressions (Galatians 3:19), which some interpret to mean that God gave the law to restrain sin--through revelation and punishments. In I Timothy 1:9, the author states that "the law is laid down not for the innocent but for the lawless and disobedient" (NRSV). But, for Rabbi Jochanan ben Zakkai, there can come a point when the people are so wicked that not even the law can restrain them.
I'm not sure how Jochanan had the power to end that ritual, since he wasn't in charge of the temple, the place where the ritual occurred. Maybe he told enough people that the law no longer applied, so they no longer felt obliged to obey it (at least not in that particular case).
Since the temple had not been destroyed yet, the Mishnah may be saying that God destroyed Jerusalem for the sins of the Israelites. The Mishnah says that adultery was rampant when the temple still stood, and isn't it interesting that Jesus also called his generation wicked and adulterous (Matthew 12:39; 16:4; Mark 8:38)? It was religious in so many respects, but many people appear to have had no problem with adultery, at least according to certain tellings.
Our generation has the same problem. I've heard stories of pastors and worship leaders who have ditched their wives to marry some babe, but they continue on in their religious service, without even batting an eye. How does one account for that sort of behavior? Shouldn't the fear of God hold them back, at least in some capacity?