Jewish ritual purity in marital relations (Niddah)

[newlybennoach]

No, they do not apply.

But a Noahide couple can mutually choose to observe some aspects of "family purity" - for example refraining from relations, or even from physical contact all together, during the days of the wife's menstration.

I have wondered why the laws of purity do not apply to Noahides. From the Torah text of Vayikra 18, when HaShem is listing the bad behaviors of the nations who have been in the land prior to Israel, approaching a woman in her time of separation for sexual activity is listed. If the nations were being punished for this, why is it not included in the mitzvot for bnei noach?

And thou shalt not approach unto a woman to uncover her nakedness, as long as she is impure by her uncleanness.
Leviticus 18:19

Defile not ye yourselves in any of these things; for in all these the nations are defiled, which I cast out from before you.
Leviticus 18:24


It seems to me that HaShem is saying the nations defiled themselves by practicing this, along with the other forbidden sexual relations. Can someone help me understand why this particular one is not included in forbidden behavior for noahides?

Andrew