What the heck was going on with the Corinthians? Why did they struggle so much with the law of chastity?

According to GotQuestions.org, “First Corinthians addresses several issues of sexuality. There was a large following of the cult of Aphrodite among the Gentiles in Corinth—her temple was atop the Acrocorinthus, and her worship involved temple prostitution. In fact, the city had so many prostitutes that well-known Greeks, including Plato, openly referred to prostitutes as “Corinthians.” Although many natives of Corinth placed faith in Jesus, many were still influenced by their immoral surroundings, which promoted sexual immorality.” (Source)