Mother of the Heir
Faustina’s main role was to set an example as a good (if not the best) woman of the Empire. She was the wife of the emperor, after all. She is intentionally associated with all kinds of female virtues like loyalty, generosity and physical beauty, but the most important one is probably motherhood. Especially to highborn Romans, a woman was really only as good as her ability to bear children. If a wife seemed not to be able to provide her husband with children, this was grounds for divorce.
Interestingly, the rumors about Faustina contradicted exactly these female virtues. First, she was made out to be disloyal and immodest, having many affairs during her marriage to Marcus Aurelius. She is said to have had a preference for the ‘rough’ types: sailors, soldiers and gladiators - maybe because her husband was the opposite, a studious philosopher.
These rumors about Faustina need not have been false. Maybe she did enjoy the company of various lovers, even gladiators. Marcus Aurelius never acknowledged any of the rumors about Faustina, at least as far as we know. He chose instead to highlight her virtue as a wife and mother, maybe as a strategy to save his own reputation and that of his heir Commodus.