Some women were freed by their owners for the purposes of marriage, in which case the grant of freedom created the obligation to marry. If she refused, she would have been seen as ungrateful and undeserving of her freedom. The status of wife did give her the option of divorce, but with her husband as her patron, that may have been difficult. In the first century BCE the Julian Marriage Laws forbade men of senatorial status from marrying freedwomen. Instead, the status of concubine was considered more appropriate.* By the second century, even middle class freeborn men who wished for a recognized relationship with a freedwoman, their own or of others, were generally encouraged to take them as concubines rather than marrying them.
Some freedwomen married coliberti, men who had been slaves of the same master with them. Often these couples were already in a de facto marriage, known as contubernium. It was not uncommon for a woman to be freed so that her relationship with her already freed partner could be made legal. Freedwomen who married neither a colibertus nor their former owners usually married other freedmen or no one. Some did marry freeborn men, but as time went on, such unions were discouraged more and more, though this was more likely to be ignored in the lower classes. There were also women who became concubines of freeborn men not their former owners.** Often these were women who had been freed by women. The anxiety about a former slave woman’s sexuality carried over even if she became a concubine.
*If you’ve never read anything on Roman concubinage please go read something about it before making assumptions. It’s probably not really what you think it is.
**Granted, considering that one jurist basically defined marriage as “it’s a marriage if they claim affectio maritalis and can legally marry; it’s concubinage if they say it’s concubinage,” another’s words basically boil down to “assume marriage if she’s free, they’re living together, and she’s not a prostitute,” and a third bases it entirely on the relative statuses of the partners, defining whether a woman was a wife or a concubine could sometimes get a little sticky, from a legal standpoint at least.
Lefkowitz, Mary R. and Maureen B. Fant, trans. Women’s Life in Greece and Rome: a Source Book in Translation. Baltimore, MD: Johns Hopkins University Press, 1992.
Perry, Matthew J. Gender, Manumission, and the Roman Freedwoman. New York: Cambridge University Press, 2014.
Pomeroy, Sarah B. Goddesses, Whores, Wives, and Slaves. New York: Schocken, 1995.
Treggiari, Susan. Roman Freedmen During the Late Republic. Oxford University Press, 1969.