You mean as regards the number of wives. while,
in Law, Sex, and Christian Society in Medieval Europe, Brundage writes that “Romans generally tolerated a wide variety of sexual practices. Prostitution, concubinage, masturbation, and homosexual relations all carried no social or moral opprobrium” (Brundage 44). In other words, the pre-Christian society of the early Imperial Empire showed little sign of the sexual ascetism and anti-homosexuality that would later arrive with the development of Christianity. Literature from pre-Christian Rome shows a similar indifference towards sexual preference: in Clitophon and Leucippe, a novel read by Romans of the third century, homosexual and heterosexual romantic love appear as absolutely indistinguishable—with the factor of gender treated merely as an accident (Boswell 86). In fact, the existence of literature with homosexual relationships and the indifference with which sexual orientation is treated in it even suggests that same-sex relationships were quite common. In any case, both these pieces of evidence reflect a society that was comfortable with various expressions of sexuality and homosexual relationships. However, perhaps the most concrete evidence of the early Roman Empire’s tolerance of homosexuality comes from the written law. In the early Empire, same-sex relations were definitely legal; institutionalized same-sex relationships were actually becoming more common just as long-term, different-sex marriages were growing in popularity. - https://pdxscholar.library.pdx.edu/cgi/viewcontent.cgi?article=1074&context=younghistorians
Pederasty was so common in Roman society and so many young boys were being pursued that rules had to be put in place to protect the freeborn roman... -https://www.ipl.org/essay/Pederasty-The-Role-Of-Masculinity-In-Ancient-FCJHAE7UZV
The Roman view of pederasty was arguably the loosest. Whereas the Samurai and the Greeks viewed it as a spiritual or educational union, the Romans simply engaged in it as a social pastime. In Ancient Rome, it was actually socially normal for older men to prefer younger boys over young women. However, sodomy was still frowned upon, so the only young men available to become sexual partners were slaves, whose rights were unprotected. Pederasty was common practice in the Roman Empire until the rise of Christianity, which, as it did in Greek culture, put a stop to the practice of sodomy by condemning homosexuality. - https://allthatsinteresting.com/pederasty/2
Immorality as it is defined in a modern context has no Roman equivalent... The Roman obsession with appearances and upholding mos maiorum creates a seeming dichot- omy between the behavior expect- ed from those in an honor-shame culture and the general fixation on personal indulgence and fulfillment. Immorality was a foreign concept to the ancient Romans; they were concerned with maintaining the ap- pearance of propriety rather than with denying themselves sexual gratification and the exploration of vices. Excessive self-indulgence was frowned upon as not exemplifying the true characteristics of the proper Roman. Sexual activities were regulated by the mos maiorum and were considered to be ordinary aspects of Roman society. Acts that were daily behaviors for the Romans could be considered unusual, im- moral, or even obscene in a different cultural framework.
From Romulus to Augustus adultery occurred and was considered to be the extramarital relationship by or with married women. According to the law of this period, the unfaithful wife's adultery was always a crime, but the husband's only if committed with a married woman. The unfaithful wife faced prosecution with severe punishment, such as death and exile. She also faced financial penalties related to the dowry. If death or exile was too grave she was divorced, faced infamia or lost certain of her limited rights. In early law she was privately judged by a family council. By the time of August she was prosecuted in a public criminal court. The unfaithful husband escaped all of this. - http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-545X2015000200004
As you so eloquently point out, the Roman pagans influenced Christianity, even the Catholic priests’ penchant for abusing young boys.