In Roman law of the 1st century, it was illegal for a man or woman to not be married between the ages of 25-60 (for men) and 20-50 (for women). So for the Romans celibacy was a crime, and there were restrictions on those who were celibate, this is one of the many issues that put Christians at odds with the Roman empire. Especially Paul, because he was celibate and encouraged (but did not require) celibacy in 1 Corinthians 7.
Lex Papia Poppaea established around 9 AD, was the legal framework for Roman Marriages by the 1st century. This law extends marriage laws made almost two decades before it referred to Lex Julia (de Maritandis Ordinibus and de Adulteriis Coercendis). Men between 25 and 60 and Women between 20 and 50, were required to be married by law unless there was some special exception. Augustus instituted the “Law of the three sons” which favored men who has at least three male heirs. Celibacy within the marriageable age range was frowned upon and punished. Adultery was generally punished by exile to islands, and each offender was sent to a different island. Also, there was the confiscation of half of an offender’s property. Fathers were permitted to kill adulterous daughters and their partners, and husbands could kill the cheating partner under certain circumstances. The men were required to divorce their adulterous wives. Caesar Augustus himself banished his daughter Julia and her eldest daughter Julia the Younger in accordance with the law. The divorce laws were pretty lax in Roman and one could simply leave their spouses home (or kick them out) for a divorce, there was no special requirement, nor a legal document confirming the divorce. Caesar did not care who was married to whom, but it did matter that everyone was married to someone for the purpose of making babies and growing the empire.
It’s worth taking note of things like this so that we can properly contextualize the culture of the new testament. This way when reading about subjects like marriage and divorce we can see why Jesus or Paul said what they said to whom they were talking. This gives us background on what the Gentiles believed about these subjects before becoming Christians. Jesus and Paul don’t denounce divorce but they do give it proper biblical contextualization by referencing the Torah’s requirements for divorce. Their teachings on the subject were in contrast to both the 1st Jewish redefining of divorce rules written in the Talmud and the Roman customs that Gentile believers had come from. You can read my essay on divorce in the new testament here.