What differentiates ethos from morality is the citta. In MN54 we read:
Potaliya the householder, while walking and wandering for exercise, wearing full dress with parasol and sandals, also went to the grove, and having entered the grove, he went to the Blessed One and exchanged greetings with him. When this courteous and amiable talk was finished, he stood at one side. The Blessed One said to him: “There are seats, householder, sit down if you like.”
When this was said, the householder Potaliya thought: “The recluse Gotama addresses me as ‘householder,’” and angry and displeased, he remained silent.
A second time the Blessed One said to him: “There are seats, householder, sit down if you like.” And a second time the householder Potaliya thought: “The recluse Gotama addresses me as ‘householder,’” and angry and displeased, he remained silent.
A third time the Blessed One said to him: “There are seats, householder, sit down if you like.” When this was said, the householder Potaliya thought: “The recluse Gotama addresses me as ‘householder,’” and angry and displeased, he said to the Blessed One: “Master Gotama, it is neither fitting nor proper that you address me as ‘householder.’”
“Householder, you have the aspects, marks, and signs of a householder.”
For a householder, genitalia is the sign to take as it lasts as long as the body lasts:
It would be better for the uninstructed run-of-the-mill person to hold to the body composed of the four great elements, rather than the mind, as the self. Why is that? Because this body composed of the four great elements is seen standing for a year, two years, three, four, five, ten, twenty, thirty, forty, fifty, a hundred years or more. But what’s called ‘mind,’ ‘intellect,’ or ‘consciousness’ by day and by night arises as one thing and ceases as another. Just as a monkey, swinging through a forest wilderness, grabs a branch. Letting go of it, it grabs another branch. Letting go of that, it grabs another one. Letting go of that, it grabs another one. In the same way, what’s called ‘mind,’ ‘intellect,’ or ‘consciousness’ by day and by night arises as one thing and ceases as another.
In traditional roles, households is the duty of a woman. Only a purisa can become sakka/indra:
Unchastity is the taint in a woman; niggardliness is the taint in a giver. Taints, indeed, are all evil things, both in this world and the next
So, the issue of superiority between monogamy and polyamory has more to do with moralizing than with ethos. In this context, may i share the following by Bertrand Russell:
Many a marriage hardly differs from prostitution, except being harder to escape from.