Couples usually resorted to concubinage when inequality of social rank was an obstacle to marriage: for instance, a man of senatorial rank, and a woman who was a social inferior, such as a freedwoman or one who had a questionable background of poverty or prostitution.
As parellas adoitaban acudir ao concubinato cando as desigualdades sociais eran un obstáculo para o matrimonio; por exemplo, un senador e unha muller liberta ou unha muller de rango social inferior con antecedentes de pobreza ou prostitución.