Couldn't Niniel and Turin work this out?

[Eorl of Rohan]

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One of my favorite features in Barrow-Downs is the ever-changing quotes on the top right corner, and today it showed this passage:

NINIEL, THINKING TURIN IS DEAD:
"Farewell, O twice beloved! A Túrin Turambar turun ambartanen: master of doom by doom mastered! O happy to be dead!"

This reminded me, what if Niniel knew that Turin was just out cold and not dead? Would she have killed herself regardless?
I know that she was pregnant (and thus her hormones might have added to her impetuousness),
but couldn't Niniel the Tearmaiden pause and assess her situation?
I mean, brother marries sister in lots of cultures (especially in royal families, to keep the bloodline pure),
And I suspect that Niniel didn't receive much of ethical or moral sermons on sexual purity from Morwen while on the road;
Even if she did, nowhere on Silmarillion does Eru or the Valar state: "thou shalt not marry thine own brethren".
Why would it be a sin? It would be weird, but not Oedipal marry-your-mother weird. Besides, isn't suicide/infanticide sinful as well?

Don't you think Niniel and Turin might have worked out a viable solution other than double-suicide to this tangled web of deceit,
if Niniel realized in time that Turin was unconscious but still alive? Somehow overcome this, together?

I know that I'm a sucker for happy endings, but I cannot help but wonder whether Niniel would've killed herself she knew Turin lived.
I understand her jumping off a cliff in her despair at her husband's death and the shock of what she found out,
But what would Niniel and Turin have done if Niniel knew Turin was alive? (I assume filing for divorce wasn't an option, but still.)
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