Up until the First and Second Lateran Councils (early 12th century), it was perfectly legal within the Church for a priest to get married. Many of them did just that. Indeed, many parishes, especially those in rural areas, preferred that their priest have a wife. A married man was considered more stable than an unmarried one, an idea that applied to priests as well as laymen. In many places the priest’s wife held a certain amount of prestige and responsibility by virtue of being married to him. Many sons of priests went on to be priests themselves. People had so much invested in this system that many bishops who tried to tell their priests to give up their wives found themselves fleeing an angry mob.
Given all of that, it’s pretty unsurprising that the 12th century ban on clerical marriage didn’t have much practical effect. In most places all that really happened was that priests continued to live with women as though they were married. While this was technically concubinage and fornication, most priests and their parishes ignored what the higher-ups had to say and continued to do things the way they had previously. Though they weren’t technically married, many of these concubines held much of the same status in the villages as a priest’s wife would.
The ban proved mostly ineffective, especially at first. When their superiors cracked down on them, priests simply tried to be more discrete. It was only during the Reformation, when the Church started educating its clerics much more systematically that the idea of the priest’s wife or concubine (his wife in all but law) as an integral part of the parish died out.
*Or really anywhere Christianity was prominent. Neither the Eastern Orthodox nor the Coptic Churches have ever prohibited their priests from marrying. A priest may not marry after his ordination, but being already married is no impediment. Indeed, many Byzantine convents preferred that their priests and father confessors be married.
**The irony here is that the Church didn’t succeed in stopping most of its priests etc. from having sex or getting married until after the Protestants split off and decided that clerical celibacy was a stupid and unworkable idea.
Brundage, James A. Law, Sex, and Christian Society in Medieval Europe. Chicago: University of Chicago Press, 1987.
Parish, Helen L. Clerical Celibacy in the West, c. 1100-1700. Burlington, VT: Ashgate Publishing, 2010.
Armstrong-Partida, Michelle. "Priestly Marriage: the Tradition of Clerical Concubinage in the Spanish Church." Viator 40.2 (2009): 221-253. (Also found here.)
Clerical Marriage - Wikipedia
Clerical Celibacy - Wikipedia