Quite a general question there as you could say different things entirely depending on what period specifically you're looking at!

I've done research into virginity and adultery in late Republican/early Imperial Rome. High literature frequently expresses that women were expected to remain pure and chaste until marriage - many moralising stories existed such as that of Lucretia, who committed suicide after being raped, and Verginia, whose father killed her to save her becoming a sex slave. There was even a goddess of chastity - Pudicitia - who was to be worshipped by unmarried virgin women, and several epitaphs praise women for acting chastely their whole lives. Then there were the Vestal virgins, a small group of upper-class girls who were expected to remain virgins for the length of their service to Vesta - if they were thought to have been unchaste, they were reportedly buried alive.

I read a fantastic article recenly by Sandra Joshel, who argues that the importance of women's chastity in Rome was directly linked to the honour and restraint of the men around them - essentially, the chasteness of women was a pillar holding up the moral standing of Rome.

However, the laws and attitudes we find in high literature can't really be said to reflect reality because they are so moralising. Augustus' laws were made predominantly with the upper classes in mind, and unfortunately because of the under-representation of lower classes and marginalised groups in the literature we have very little idea what the lower classes were up to - but we do know that slaves were in reality subject to whatever their master desired, that brothels were rife, and that there was a lot of backlash from married women against Augustus' marriage reforms, which made adultery illegal - not much research has been done into it, but I believe it was the case that lower class married women prostituted themselves for financial reasons. There are also examples of upper-class women such as Clodia, Sempronia, and two of Claudius' wives whose power and sexual promiscuity made them infamous.

(Edit: clarity)