Allow me to quote myself:
I’d recommend Cardinal Stickler’s Book . Priests in the early Church were expected to practice continence, that is, they had to completely abstain from sex after ordination.
The statement in 1 Timothy, that a bishop must be faithful to his one wife, is often misinterpreted as meaning a bishop ought to be married. Actually, the intent is that he not have more than one wife. Was this a prohibition against polygamy? No, that was already forbidden to all Christians. Was it a prohibition against divorce and remarriage? No, again, that was already prohibited, and back then all Christians understood it to be prohibited. It was actually a prohibition against allowing a man who was widowed and remarried from becoming a bishop.
Why the prohibition? Well, the Cardinal explains that to have remarried after being widowed was evidence that continence would be a difficult lifestyle choice for such a person.
He also explains that the Council of Elvira, in approximately the year 305, adopted continence in canon law. He argues further that this couldn’t have just been adopted out of the blue. It had to have been widely understood to have been the longstanding tradition of the Church, or there would have been widespread rebellion among the priests.
By the tenth or eleventh century, the Church was finding more noncompliance with the continence requirement, in part, I think, due to widespread ignorance. At the same time, monasterries were growing, which provided a pool of never married men who could become priests, so they eventually decided against allowing married men
Yes, there were married priests and bishops. Peter was married, as you note. *But *all historical evidence indicates that they were required to live as though they were not married. A married pope in the future is a theoretical possibility, but the odds are against it, to put it mildly.