a respectful and faithful attachment to gods, country, and relatives, especially parents
Wikipedia has this:
Around the year 70 BC, Cicero defined pietas as the virtue "which admonishes us to do our duty to our country or our parents or other blood relations."
According to the Nova Roma website:
More than religious piety, it is closer to the idea of "Dutifulness", a respect for the natural order socially, politically, and religiously. This includes the ideas of patriotism and devotion to others.
Sondra Steinbrenner writes that:
Pietas is a traditional Roman value which can be defined as duty, honor, and responsibility to others, and the taking of these obligations seriously.
The hero Aeneas was said to embody the virtue of pietas:
Aeneas ... represents "pietas" which to the Romans meant dutifulness, doing what was right for the family, the community, the civilization, and the gods.
The idea of pietas seems to be that it is part of the natural law to demonstrate a loving devotion to your family, to your nation and to the gods and that the duty towards others derived from this should override impetuous acts of selfish emotion.
I think we can learn from the ancient Romans when it comes to this particular virtue.