I found a (Dutch) article about this in the "Historisch Nieuwsblad" (https://www.historischnieuwsblad.nl/nl/artikel/26822/het-celibaat-van-de-katholieke-kerk.html), a primary source for that article is 'Die Geschichte des Zölibats' (1993) by Georg Denzler and furthermore a Dutch translation of Confessiones by Augustine of Hippo and 'Eunuchen voor het hemelrijk. De Rooms-katholieke kerk en seksualiteit' (1990) (Eunuchs for the Kingdom of Heaven. The roman-catholic church and sexuality) by Uta Ranke-Heinemann.

The article describes that Pope Gregory VII (Pope from 1073 till his dead in 1085, ) summoned a council in the Lateran palace in 1074, which confirmed celibacy as an ideal. A year later he published a papal decree that said that all priests and deacons should live a celibate life. The only exception was made for those who were already legitimately married. But no new marriages were allowed. There were violent uprisings by furious priests all over Europe, but it was a turning point in a discussion that already spanned centuries. Origen, one of the Church Fathers (c 184-c235) was believed to have castrated himself to save himself from lust (even though he never wrote about it and denied it when an opponent accused him of doing so, but for centuries he was an example to many).

During the First Council of Nicaea in 325, celibacy was discussed. After fiery debate it was decided that celibacy was a personal choice. But because it was such a heated debate, many people wrote about their opinion. Augustine of Hippo for instsnce, wrote in his work Confessiones how he lives a sinful life filled with carnal lust. He begs God for chastity, just not yet. He talks about how his desire for his partner is clouding his relationship with God. In his work, he compares the body and mind to mankind and God. A man, for instance, can have an erection when he doesn't want to or no erection when he does want it. At that moment his body does not obey his mind. The flesh resists the will, as mankind resists God. Eventually Augustine finds the strength to send his wife and son away and surrenders himself to God.

This is the Neoplatonic doctrine and has nothing to do with the teachings of Jesus, who did not demand celibacy from his disciples. Saint Peter, the first Pope, was married. Chastity was a choice, made by some, but definitely not all. Helvidius (or Helveticus), Jovinian and Paphnutius believed celibacy was a recommendation, but marriage was also a holy union. When christianity spread across Europe, celibacy was difficult to sell to the newly baptised Franks, Saxons and other cultures and many priests and bisshops chose a married life. It appeared that the pro-celibacies had lost.

However, as the centuries went by, becoming a religious man was a lucrative career: you did not have to pay taxes and you did not have to fight in combat. Many powerful clergymen were more loyal to their dynasty than to the Pope. And because not all of their children chose a career in the church, a lot of wealth was lost to Rome. Not all popes cared, many enjoyed a life of worldly politics, booze and sex, but primarily popes with a monasterial background started to discuss obligatory celibacy.

There was a power struggle between emperors and popes during the 11th and 12th century and a growing number of clergyman believed that the church had to completely separate itself from the worldly powers. In order to do that, they even rewrote history, during the First Lateran Council in 1123, priests were no longer allowed to live with their married partners. Participants justified that by claimimg that marriage had already been banned for priests during the First Council of Nicaea.

In 1139, during the Second Lateran Council celibacy became obligatory. Not as a theological dogma: being married became a punishable offence. A married priest was excommunicated, their children were not allowed to become priests. At least, that was the theory. Arnoud-Jan van Bijsterveld published his thesis 'Laverend tussen kerk en wereld'(navigating between church and world) in 1993. He researched the Dutch diocese of Brabant and saw that a third of all priests were fined for not living celibate, many priests were fined every year and 80% of all fines were given for sexual misconduct. Many of the women were described as the 'housekeeper' or 'partner'. It was accepted by the church as they believed it to be less toxic than having sex with many people. As long as it wasn't a public scandal a fine was seen as an appropriate punishment. After the Reformation protestants mocked the catholic church for the enormous gap between theory and practice and as a result the catholic church became less and less tolerant for concubines and housekeepers.