Roman emperors Honorius and Theodosius II issue a new law forbidding Christian priests from living with women other than their wives, mothers, sisters, or daughters. Christian priests are also protected from being separated from their wives.
According to this new Roman law:
"Living as a religious priest requires a commendable discipline. In accordance with good morals, priests who serve the sacred ministries must not consort with extraneous women — not even with the excuse of calling them "sister." ...
The only concession is that he may have within his own home his mother, daughters, and sisters — these natural bonds permit no perverse crime to be considered.
Moreover, those women who were lawfully married before their husbands became priests must not be deserted. These women have made their husbands worthy of the priesthood by their association are not unsuitably joined with clerics. ..." [CS 10]
This law is repeated elsewhere:
"It is not seemly that a man who lives a commendable life of discipline in the priesthood become tarnished by the intimate association of a so-called "sister." For anyone in the priesthood at any level, consorting with extraneous women is forbidden. The only concession granted to him is living in his own home with his mother, daughters, and sisters because these natural bonds permit no consideration of perverse crimes.
Moreover, women who were legally married prior to their husbands become priests may not be deserted. Those women have made their husbands worthy of the priesthood by their association are not unsuitably joined to clergy." [CT 16.2.44]
Absolute clerical celibacy is not yet a requirement, which is why priests have wives and are permitted to keep wives. Apparently, though, merely having a wife isn't quite good enough for some of them, and they have intimate relations with other women as well.